Exhibit 10.2





                       LIMITED LIABILITY COMPANY AGREEMENT

                                       OF

                          PSMA DEVELOPMENT COMPANY LLC





                               Dated June 15, 1999








                                TABLE OF CONTENTS


ARTICLE I FORMATION AND NAME:  OFFICE; PURPOSE; TERM..........................1

   1.1. Organization..........................................................1
   1.2. Name of the Company...................................................1
   1.3. Principal Place of Business...........................................1
   1.4. Purpose...............................................................1
   1.5. Company Authority.....................................................2
   1.6. Term..................................................................2
   1.7. Registered Agent......................................................2
   1.8. Members and Initial Contribution......................................2
   1.9. Additional Members....................................................2

ARTICLE II CAPITALIZATION.....................................................2

   2.1. Capital Accounts......................................................2
   2.2. Capital Contributions.................................................3
   2.3. Loans.................................................................6
   2.4. Budget................................................................6

ARTICLE III PROFITS, LOSSES AND DISTRIBUTIONS.................................7

   3.1. Allocation of Profits and Losses......................................7
   3.2. Allocation-Rules......................................................9
   3.3. Tax Allocations: Section 704(c) of the Code...........................9
   3.4. Fiscal Year..........................................................10
   3.5. Partnership for Tax Purposes.........................................10
   3.6. Tax Matters..........................................................10
   3.7. Cash Flow Distributions..............................................11
   3.8. Liquidating Distributions Upon Dissolution...........................11
   3.9. Tax Distributions....................................................11
   3.10. Deficit Capital Account Restoration.................................12
   3.11. Other Distributions.................................................12

ARTICLE IV MANAGEMENT........................................................12

   4.1. Management Committee.................................................12
   4.2. Meetings of Members..................................................18
   4.3. Liability and Indemnification........................................18
   4.4. Duties, Right to Conduct Other Business..............................19
   4.5. Scientific Advisory Board............................................20
   4.6. Research Grants......................................................20

                                       i



ARTICLE V OFFICERS...........................................................20

   5.1. Designation, Authority and Compensation of Officers..................20
   5.2. Tenure of Officers...................................................20

ARTICLE VI TRANSFER OF INTERESTS, WITHDRAWAL AND TERMINATION OF MEMBERS......20

   6.1. Transfer or Withdrawal Prohibited; Change of Control of a Member.....20
   6.2. Regulatory Matters...................................................22
   6.3. Default; Buyout/Liquidation Option...................................22

ARTICLE VII DISSOLUTION, LIQUIDATION AND TERMINATION OF THE COMPANY..........26

   7.1. Events of Dissolution................................................26
   7.2. Procedure for Winding Up and Dissolution.............................26
   7.3. Termination of Company...............................................26
   7.4. License Grants on Dissolution........................................26

ARTICLE VIII BOOKS, RECORDS, ACCOUNTING AND TAX ELECTIONS....................27

   8.1. Bank Accounts........................................................27
   8.2. Fiscal Year..........................................................27
   8.3. Method of Accounting.................................................27
   8.4. Books and Records....................................................27
   8.5. Tax Information......................................................27

ARTICLE IX MARKETING RIGHTS..................................................28

   9.1. Grant of North American Marketing Rights.............................28
   9.2. Diligence Obligations................................................28
   9.3. Assistance by Progenics; Contingent Grant of Rights..................28
   9.4. Marketing Agreement..................................................29
   9.5. Negotiation Rights...................................................30
   9.6. Marketing Compensation...............................................31
   9.7. Non-Transferability of Rights........................................31
   9.8. Termination of Rights................................................31
   9.9. Retention of Rights..................................................32

ARTICLE X DISPUTE RESOLUTION.................................................32

   10.1. Escalation Procedure................................................32
   10.2. Arbitration.........................................................32
   10.3. Injunctive Relief...................................................34

ARTICLE XI MISCELLANEOUS PROVISIONS..........................................34

   11.1. Assurances..........................................................34
   11.2. Disclaimer of Agency................................................34

                                       ii




   11.3. Entire Agreement; Amendment.........................................34
   11.4. Notices.............................................................34
   11.5. Counterparts........................................................35
   11.6. Governing Law.......................................................35
   11.7. Binding Effect......................................................35
   11.8. Severability........................................................35
   11.9. Survival of Rights, Duties and Obligations..........................35
   11.10. Captions and Exhibits..............................................35
   11.11. Specific Performance...............................................35
   11.12. Assignability......................................................35
   11.13. Confidentiality....................................................36











                                      iii




                       LIMITED LIABILITY COMPANY AGREEMENT

                                       OF

                          PSMA DEVELOPMENT COMPANY LLC

                  This Limited Liability Company Agreement (this "Agreement") is
made this 15th day of June, 1999, by and among Progenics Pharmaceuticals,  Inc.,
a  Delaware  corporation   ("Progenics"),   CYTOGEN   Corporation,   a  Delaware
corporation  ("CYTOGEN"),  and PSMA Development  Company LLC, a Delaware limited
liability company (the "Company").

                              EXPLANATORY STATEMENT

                  The parties  have  agreed to organize  and operate the Company
pursuant to the Delaware Limited Liability Company Act (the "Act") in accordance
with the terms and conditions set forth herein.

                  NOW,  THEREFORE,  for good  and  valuable  consideration,  the
parties, intending to be legally bound, agree as follows:

ARTICLE I.........
                    FORMATION AND NAME: OFFICE; PURPOSE; TERM

     1.1.  Organization.  The parties have organized the Company pursuant to the
Act and the provisions of this  Agreement  and, for that purpose,  have caused a
Certificate of Formation (the "Certificate"), in the form attached as Exhibit A,
to be executed and filed as required by the Act.

     1.2. Name of the Company. The name of the Company shall be PSMA Development
Company LLC, and all Company  business must be conducted under that name or such
other name that complies with  applicable  law as the  Management  Committee (as
hereinafter defined) may select from time to time.

     1.3. Principal Place of Business. The Company's principal place of business
shall be c/o  Progenics  Pharmaceuticals,  Inc.,  777 Old Saw Mill  River  Road,
Tarrytown,  New York  10591 or any other  place of  business  as the  Management
Committee may from time to time deem advisable.

     1.4. Purpose. The purposes of the Company are to:

     (i) acquire,  exploit,  control and distribute  all  licensing/sublicensing
rights  regarding  products in the Field, as such term is defined in Section 1.9
of the  PSMA/PSMP  License  Agreement,  dated  the  date  hereof,  by and  among
Progenics, CYTOGEN and the Company (the "PSMA/PSMP License Agreement");



     (ii)  research,  develop,  manufacture  or have  manufactured,  market  and
promote or have  marketed and promoted and otherwise  commercialize  products in
the Field;

     (iii) raise capital for the foregoing;

     iv)  engage  in any and all  things  necessary,  convenient  or  incidental
thereto; and

     (v)  engage in any other  business  or  activity  lawful  under the Act and
authorized by the Management Committee.

     1.5. Company  Authority.  The Company shall have the power and authority to
take any and all actions necessary, appropriate,  convenient or incidental to or
for the  furtherance  of the purposes  set forth  herein,  including  all of the
powers of a limited liability company under the Act.

     1.6.  Term.  The term of the Company (the "Term")  shall  commence upon the
date the  Certificate  is filed as  required  by the Act and shall be  perpetual
unless terminated as provided in this Agreement.

     1.7.  Registered  Agent.  The name and address in Delaware of the Company's
registered  agent upon whom and at which  process  against  the  Company  can be
served is Corporation Service Company,  1013 Centre Road,  Wilmington,  Delaware
19805,  or such other person or such other  persons as may be  designated by the
Management Committee.

     1.8. Members and Initial Contribution.  The names, taxpayer  identification
numbers and present  mailing  addresses  of the members (the  "Members")  of the
Company  are set forth in  Schedule A attached  hereto.  The  initial  ownership
interest  in the  Company  of each of  Progenics  and  CYTOGEN,  as the  initial
Members,  shall be 50%.  Each Member's  interest in the Company (an  "Interest")
shall at all times be equal to such Member's  Percentage,  as defined in Section
2.2 hereof.  The  Interest of each Member is subject to change from time to time
as provided herein. Each of Progenics and CYTOGEN is admitted as a Member of the
Company  effective  contemporaneously  with the execution by such person of this
Agreement.

     1.9. Additional Members.  Additional persons or entities may be admitted as
Members of the Company  only upon the prior  written  consent or approval of the
Management  Committee,  which may grant or  withhold  admission  in its sole and
absolute discretion.

                                   ARTICLE II
                                 CAPITALIZATION

     2.1.  Capital  Accounts.  (a) An individual  capital  account (the "Capital
Account")  shall be maintained  for each Member in  accordance  with the capital
account  maintenance rules set forth in Treasury  Regulation Section 1.704-1(b).
Without  limiting the generality of the foregoing,  a Member's  Capital  Account
shall be increased by (a) the amount of money  contributed  by the Member to the
Company,


                                       2



     (b) the fair market value of property (other than Intellectual Property (as
defined below) unless all Members shall agree to assign a value to such property
for  purposes of this  Article II  hereafter  contributed  by such Member to the
Company, net of liabilities secured by such property, and (c) allocations to the
Member of the Company's net income and gains (as  determined  for federal income
tax purposes  but on the basis of the book values of the  Company's  assets).  A
Member's  Capital  Account  shall  be  decreased  by (i)  the  amount  of  money
distributed  to the Member,  (ii) the fair market value of any  property  (other
than any Intellectual Property transferred previously by Progenics or CYTOGEN to
the Company without any value being reflected in the transferor Member's Capital
Account if such property is reconveyed to the transferor Member)  distributed to
the Member, as determined by the distributee  Member and the Company (net of any
liabilities  secured by the property)  after  adjusting  each  Member's  Capital
Account  by such  Member's  share  of the  unrealized  income,  gain,  loss  and
deduction inherent in such property and not previously reflected in such Capital
Account,  as if the property had been sold for its then fair market value on the
date of distribution,  (iii)  expenditures  described,  or treated under Section
704(b) of the Code as described,  in Section  705(a)(2)(B) of the Code, and (iv)
the Member's  share of losses and  deductions.  For purposes of this  Agreement,
"Intellectual  Property"  shall  include  inventions  (patented or  unpatented),
improvements, rights under patents and patent applications, unpublished research
and development information,  formulae,  processes,  expertise,  know-how, trade
secrets and technical data.

     (b) This Section 2.1 and the other provisions of this Agreement relating to
maintenance of Capital Accounts are intended to comply with Treasury  Regulation
Section  1.704-1(b) and shall be interpreted and applied in a manner  consistent
with such Treasury  Regulations.  In the event the  Management  Committee  shall
determine that it is prudent to modify the manner in which the Capital Accounts,
or any debits or credits  thereto,  are  computed  in order to comply  with such
Treasury  Regulations,  the  Management  Committee  may make such  modification;
provided,  however,  that it shall not have an  adverse  effect  on the  amounts
distributable to any Member.

     2.2.   Capital   Contributions.   (a)  Each   Member's   share  of  Capital
Contributions and each Member's  Percentage (each as defined  hereinafter) shall
be set forth on Schedule A, which shall be updated by the  Management  Committee
upon any changes in any Member's share of total Capital  Contributions.  As used
herein,  (i) the term "Capital  Contribution"  shall mean a contribution  to the
capital of the Company  made by a Member  pursuant to this  Agreement,  (ii) the
term  "Percentage"   shall  mean  a  Member's  share  of  the  Adjusted  Capital
Contributions  expressed  as a  percentage  of the  aggregate  Adjusted  Capital
Contributions   of  all   Members;   and  (iii)  the  term   "Adjusted   Capital
Contributions" shall mean a Member's Capital  Contributions as adjusted pursuant
to the terms of this Agreement (but excluding,  for these purposes,  in the case
of  Progenics,  the Progenics  R&D Capital  Contributions  as defined in Section
2.2(d) hereof and the Supplemental  Capital  Contributions as defined in Section
2.2(e) hereof and, in the case of CYTOGEN, any [CONFIDENTIAL  TREATMENT HAS BEEN
REQUESTED] as defined in Section 2.2(e) hereof).

                                       3



     (b)  Simultaneously  herewith,  the Members are contributing to the Company
cash in the amounts set forth on Schedule A.

     (c) (i) The Management  Committee may from time to time, in connection with
preparing the Budget (as defined hereinafter) or otherwise, call for the Members
to   make   additional   capital    contributions   (the   "Additional   Capital
Contributions"),  in which event the Management  Committee  shall give notice to
each  Member of: (A) the total  amount of the  Additional  Capital  Contribution
being  called;  (B) the  reason the  Additional  Capital  Contribution  is being
called;  (C) each Member's  proportionate  share of the total Additional Capital
Contribution  (determined in accordance  with this Section  2.2(c);  and (D) the
date the Additional  Capital  Contribution is due and payable,  which date shall
not,  without the written consent of the Members,  be less than 30 nor more than
90 calendar days after the notice has been given.  A Member's share of the total
Additional  Capital  Contribution  shall  be equal to the  product  obtained  by
multiplying   the  Member's   Percentage  and  the  total   Additional   Capital
Contribution  required.  A Member's share shall be payable in cash, by certified
check or wire transfer.  No Additional Capital Contribution by any Member may be
made or required  to be made on an in-kind or any other  non-cash  basis  unless
consented to in writing by each of the Members.  Upon payment of the  Additional
Capital  Contributions,  the  Capital  Contributions  of each  Member  shall  be
adjusted.

     (ii) If a Member (the "Non-Contributing  Member") fails to pay when due all
or any portion of any Additional Capital  Contribution  called by the Management
Committee (the amount not contributed  being a "Failed  Contribution"),  and the
other Member (the "Contributing  Member") makes proper and timely payment of its
portion of the Additional Capital  Contribution,  then the following adjustments
shall be made:

     (1) the Adjusted Capital Contributions of the Non-Contributing Member shall
automatically  and  without  further act on the part of any party be adjusted by
reducing  the  amount  of  the   Non-Contributing   Member's   Adjusted  Capital
Contributions  by 10% (the  "Reduction  Amount")  of the  amount  of the  Failed
Contribution  and increasing the amount of the  Contributing  Member's  Adjusted
Capital Contributions by the Reduction Amount; and

     (2) the  Percentages of the Members shall be adjusted to stand in the ratio
of their  respective  Adjusted  Capital  Contributions,  and Schedule A shall be
amended accordingly.

     (iii) If a Non-Contributing Member fails to pay when due all or any portion
of any Additional Capital  Contribution called for by the Management  Committee,
the Management Committee shall give notice (a "Non-Contribution  Notice") within
15 days after the date such Additional  Capital  Contribution is due and payable
to the Contributing  Member,  and the Contributing  Member shall have the option
(but not the obligation) to make an Additional Capital Contribution by reason of
such  default  (a  "Default  Contribution")  to the  Company in an amount not in
excess of the Failed Contribution.  Any Default  Contribution,  if made, must be

                                       4



funded within 30 calendar days after  delivery of the  Non-Contribution  Notice,
or, if the Management Committee shall fail to give the Non-Contribution  Notice,
within 45 calendar days after the date such Additional  Capital  Contribution is
due and payable.

     (iv) Except as  expressly  stated  herein,  no Member  shall be required to
contribute any additional  capital to the Company,  and no Member shall have any
personal liability for any debt,  obligations,  or liability of the Company. The
rights provided in this Section 2.2(c) shall be the exclusive remedies available
to the Company and any Contributing Member against any  Non-Contributing  Member
for such  Non-Contributing  Member's  failure  to pay  when  due any  Additional
Capital Contribution called for by the Management Committee.

     (d) Progenics shall be required to make additional Capital Contributions to
the Company of up to  [CONFIDENTIAL  TREATMENT  HAS BEEN  REQUESTED] to fund the
Company's  research and development  programs as budgeted in the work plans (the
"Work Plans") described in Section 2 of the Services Agreement,  dated as of the
date  hereof,  between  Progenics,   CYTOGEN  and  the  Company  (the  "Services
Agreement"), subject to the terms and conditions described below. The amounts so
funded are  referred to herein as the  "Progenics  R&D  Capital  Contributions."
[CONFIDENTIAL   TREATMENT  HAS  BEEN   REQUESTED]   The  Progenics  R&D  Capital
Contributions shall be provided and applied when and as needed (as determined in
the  reasonable  discretion of the  Management  Committee) to fund the Company's
research  and  development  programs  through  and  including  the filing by the
Company of an  Investigational  New Drug application with the U.S. Food and Drug
Administration  (the "FDA") with respect to a product under  development  by the
Company (an "IND  Filing").  Progenics  shall not be  obligated  to fund through
Progenics R&D Capital  Contributions,  and  Progenics R&D Capital  Contributions
shall not be applied to fund (i) any clinical development or other activities of
the  Company  with  respect  to a  product  beyond  an IND  Filing  or (ii)  any
administrative or other  non-research and development  functions,  activities or
expenses.  During the period  ending with the  discharge  in full of  Progenics'
funding obligation under this Section 2.2(d),  Progenics shall have the right to
direct the application of the Progenics R&D Capital  Contributions in accordance
with the Work Plans.  Notwithstanding the foregoing, if Progenics ceases to be a
Member in the  Company  before  Progenics  has funded to the Company all amounts
required  pursuant to this Section  2.2(d),  Progenics  shall be relieved of its
funding  obligation  with respect to such portion of the  Progenics  R&D Capital
Contributions not theretofore funded.

     (e)  [CONFIDENTIAL  TREATMENT HAS BEEN  REQUESTED]  The parties intend that
such   reduction  in  Progenics'   obligation  to  make  Progenics  R&D  Capital
Contributions shall reduce Progenics R&D Capital  Contributions  applied to fund
development  of  a  vaccine-based  product.  [CONFIDENTIAL  TREATMENT  HAS  BEEN
REQUESTED]

     (f) Progenics  shall be required to make additional  Capital  Contributions
(the  "Supplemental  Capital  Contributions")  to the  Company in the  following
amounts not later than five business days after the dates indicated:

                                       5



Amount         Date
- ------         ----

$500,000       The date of this Agreement;

$500,000       On the  earlier to occur of (i) the date that is six months after
               the date of this Agreement or December 31, 1999;

$500,000       On the earlier to occur of (i) the date on which the  Management
               Committee  by written resolution identifies a lead compound for
               product development or (ii) December 31, 2000; and

$500,000       On the  earlier  to  occur  of (i)  the  date on  which  the  FDA
               approves an Investigational  New Drug application with respect to
               a Licensed Product(as defined in the PSMA/PSMP License Agreement)
               or (ii) December 31, 2001.

Notwithstanding  the foregoing,  Progenics  shall have no obligation to make any
Supplemental  Capital  Contribution if at the time any such capital contribution
is due Progenics is not a member of the Company.

     (g) No Member shall be paid interest on its Capital  Contributions.  Except
as  otherwise  provided  in this  Agreement,  no Member  shall have the right to
receive any return of or on any Capital Contribution.

     2.3. Loans. The Management Committee may, in its sole discretion, authorize
and cause the  Company to borrow  from any person  (including  a Member) on such
terms  and  subject  to  such  conditions  as  the  Management  Committee  shall
determine.  No Member  shall be  required  to lend  funds to the  Company  or to
guarantee or provide  security or any other form of credit  support with respect
to any such borrowing.

     2.4. Budget.  (a) The Management  Committee shall promptly prepare a budget
for the  Company's  activities  covering  such  time  period  as the  Management
Committee  shall  deem  appropriate.  The  Budget  may  include  provisions  for
Additional  Capital  Contributions  to  made  by  the  Members.  The  Management
Committee  shall meet to review and update the Budget on a semi-annual  basis or
as it may otherwise determine to be appropriate.

     (b) If at any time the  Management  Committee  is  unable  to agree  upon a
proposed  Budget or a proposed update to the Budget (a "Budget  Dispute"),  such
disagreement  will be  resolved  in  accordance  with  the  management  deadlock
provisions  contained in Section 4.1(f) hereof  (provided that if any portion of
the Budget is not in dispute, the provisions of such undisputed portion shall be
implemented  to the extent  practicable).  If a Budget  Dispute is  submitted to
arbitration,  and the arbitrator  determines  that a Member (the  "Uncooperative
Member") acted in bad faith in unreasonably  withholding  approval of a proposed
Budget, the Adjusted Capital  Contributions of the Uncooperative  Member and the
other Member shall  without  further act on the part of any party be adjusted by
reducing the amount of the Uncooperative Member's Adjusted Capital Contributions
by the  greater  of (A)  [CONFIDENTIAL  TREATMENT  HAS  BEEN  REQUESTED]  of the


                                       6


Uncooperative  Member's pro rata share of any  Additional  Capital  Contribution
required by the  arbitrator  (if the  dispute  involved  an  Additional  Capital
Contribution)  or  (B)  [CONFIDENTIAL  TREATMENT  HAS  BEEN  REQUESTED]  of  the
Uncooperative Member's Adjusted Capital Contributions, and increasing the amount
of the other Member's Adjusted Capital Contributions by such amount.



                                  ARTICLE III
                        PROFITS, LOSSES AND DISTRIBUTIONS

     3.1. Allocation of Profits and Losses. (a) The Company's profits and losses
(as  determined  for federal income tax purposes but as adjusted under the rules
of Treasury Regulation Section  1.704-1(b)(2)(iv)) for each Fiscal Year shall be
allocated  to the Members (i) first,  in such amounts as will adjust the Capital
Account  balances  of each of the  Members to be in the same  proportion  as the
Members'  respective  Percentages  and (ii)  thereafter,  in  proportion  to the
Members respective Percentages.

     (b)  Notwithstanding  Section 3.1(a) hereof,  losses allocated  pursuant to
Section  3.1(a) to any Member for any Fiscal  Year shall not exceed the  maximum
amount of loss that may be allocated to such Member without  causing such Member
to have an Adjusted Capital Account Deficit (as defined  hereinafter) at the end
of such Fiscal Year. Any loss in excess of the limitation in this Section 3.1(b)
shall be specially  allocated  solely to the other Members to the maximum extent
permitted by this Section 3.1(b).  "Adjusted  Capital  Account  Deficit" means a
deficit Capital Account balance after that balance has been adjusted pursuant to
the penultimate  sentences of Treasury  Regulations  Sections  1.704-2(g)(1) and
1.704-2(i)(5).

     (c)   Notwithstanding   Section  3.1(a)  hereof,   the  following   special
allocations  shall be made in the following  order prior to the  application  of
Section 3.1(a) hereof:

     (i) If there is a net decrease in Company minimum gain ("Minimum Gain") (as
such  decrease  is  determined  as provided  in  Treasury  Regulations  Sections
1.704-2(d) and 1.704-2(g))  during any Fiscal Year,  certain items of income and
gain,  including gross income or gain,  shall be allocated to the Members in the
amounts and manner described in Treasury  Regulations Section  1.704-2(f).  This
Section  3.1(c)(i)  is  intended  to comply  with the  minimum  gain  chargeback
requirement  relating to  partnership  non-recourse  liabilities  (as defined in
Treasury Regulations Section 1.704-2(b) and shall be so interpreted

     (ii) If there is a net  decrease in Minimum  Gain  attributable  to partner
non-recourse  debt  (determined   pursuant  to  Treasury   Regulations   Section
1.704-2(i)) during any Fiscal Year, certain items of income and gain,  including
gross income or gain, shall be allocated as quickly as possible to those Members
which had a share of the Minimum Gain  attributable to the partner  non-recourse
debt (such  share to be  determined  pursuant to  Treasury  Regulations  Section


                                       7



1.704-1(i)(5))  in the amounts  and manner  described  in  Treasury  Regulations
Sections  1.704-2(i) and (j). This Section 3.1(c)(ii) is intended to comply with
the minimum gain chargeback  requirement  relating to partner  non-recourse debt
set  forth  in  Treasury  Regulations  Section  1.704-2(i)(4))  and  shall be so
interpreted.

     (iii) Deductions attributable to obligations with respect to which a Member
bears the  economic  risk of loss  within  the  meaning of  Treasury  Regulation
Section  1.704-2(b)(4) shall be allocated to the Member or Members that bear the
economic  risk of loss for such  debt in  accordance  with the  requirements  of
Treasury  Regulation Section  1.704-2(i)(1).  "Nonrecourse  Deductions" (as such
term is defined in Treasury Regulations  Sections  1.704-2(b)(1) and 1.704-2(c))
of the  Company  shall  be  allocated  to the  Members  in  proportion  to their
Percentages.

     (iv) If one or more of the Members  unexpectedly  receives any  adjustment,
allocation or distribution  described in Treasury  Regulations  Sections 1.704-1
(b)(2)(ii)(d)(4),  (5) or (6),  then items of income and gain shall be specially
allocated to such Members in an amount and manner  sufficient  to eliminate  the
Adjusted  Capital Account Deficit  created by such  adjustments,  allocations or
distributions  as quickly as possible,  provided that an allocation  pursuant to
this Section 3.1(c)(iv) shall be made only if and to the extent that such Member
would have an  Adjusted  Capital  Account  Deficit  after all other  allocations
provided for in this Section 3.1 have been  tentatively  made as if this Section
3.1(c)(iv) were not in this Agreement.  This provision is intended to qualify as
a "qualified income offset" within the meaning of Treasury  Regulations  Section
1.704-1(b)(2)(ii)(d).

     (v) If one or more of the Members has a deficit  Capital Account at the end
of any Fiscal  Year which is in excess of the sum of (i) the amount  such Member
is obligated to contribute  pursuant to any provision of this Agreement and (ii)
the amount  such  Member is deemed to be  obligated  to restore  pursuant to the
penultimate  sentences  of  Treasury  Regulations  Sections   1.704-2(g)(1)  and
1.704-2(i)(5),  each such Member shall be specially  allocated  items of Company
income and gain in the amount of such  excess as quickly as  possible,  provided
that an allocation  pursuant to this Section 3.1(c)(v) shall be made only if and
to the extent that such Member would have a deficit Capital Account in excess of
such sum after all other allocations  provided for in this Section 3.1 have been
made as if Section  3.1(c)(iv) hereof and this Section 3.1(c)(v) were not in the
Agreement.

     (vi) The allocations set forth in Sections 3.1(b) and 3.1(c)(i)-(v)  hereof
(the "Regulatory  Allocations") are intended to comply with certain requirements
of the Treasury Regulations. It is the intent of the Members that, to the extent
possible,   all  Regulatory  Allocations  shall  be  offset  either  with  other
Regulatory  Allocations  or with special  allocations  of other items of Company
income, gain, loss or deduction pursuant to this Section 3.1(c)(vi).  Therefore,
the  Management  Committee  shall make such  offsetting  special  allocations of
Company  income,  gain,  loss and  deduction in whatever  manner they  determine
appropriate,  so that, after such offsetting allocations are made, each Member's
Capital Account balance is, to the extent possible, equal to the Capital Account
balance such Member would have if the  Regulatory  Allocations  were not part of


                                       8


the Agreement and all Company items were allocated  pursuant to Section  3.1(a).
In exercising its discretion,  the Management  Committee shall take into account
future  Regulatory  Allocations  pursuant to Sections  3.1(c)(i) and (ii) hereof
that,  although not yet made, are likely to offset other Regulatory  Allocations
previously made under Section 3.1(c)(iii) hereof.

     (vii)  If the  Internal  Revenue  Service  reallocates  an item of  income,
deduction or loss to a Member or an affiliate  ("Affiliate") pursuant to Section
482 of the Code or any similar rule or  principle of law (a "Member  Section 482
Allocation"), and the Company has a corresponding correlative item of deduction,
loss or income (as determined  under Section  1.482-1(g) of the Regulations (the
"Company  Correlative  Item"),  such Company Correlative Item shall be specially
allocated to and  reflected in the Capital  Account of the Member that  received
(or  whose  Affiliate  received)  such  Member  Section  482  Allocation,  and a
corresponding  deemed contribution or distribution shall likewise be credited or
debited to the Capital Account of such Member.

     (viii) If the  Internal  Revenue  Service  reallocates  an item of  income,
deduction  or loss to the  Company  pursuant  to Section  482 of the Code or any
similar rule or principle of law (a "Company Section 482  Allocation"),  and any
Member has a  corresponding  correlative  item of deduction,  loss or income (as
determined under Section 1.482-1(g) of the Regulations (the "Member  Correlative
Item")), such Company Section 482 Allocation shall be specially allocated to and
reflected in the Capital Account of the Member that received (or whose Affiliate
received) such Member Correlative Item, and a corresponding  deemed contribution
or distribution  shall likewise be credited or debited to the Capital Account of
such Member.

     (ix) If any  Member is  required  to  contribute  an amount to the  Company
pursuant to the last  sentence of Section 3.9  hereof,  special  allocations  of
gross items of income,  gain, loss and deduction shall be made to the Members to
ensure that after such  contribution  and all liquidating  distributions  to the
Members, each of the Members' Capital Account balances will equal zero.

     3.2. Allocation-Rules.  (a) For purposes of determining the profits, losses
or any other items allocable to any period,  profits,  losses and any such other
items shall be determined on a daily,  monthly or other basis,  as determined by
the Management  Committee using any method that is permissible under Section 706
of the Code and the Treasury Regulations thereunder.

     (b) The Members are aware of the income tax consequences of the allocations
made by this Article III and hereby agree to be bound by the  provisions of this
Article III in reporting  their shares of Company income and loss for income tax
purposes.

     3.3. Tax  Allocations:  Section 704(c) of the Code. (a) In accordance  with
Section  704(c) of the Code and the  Treasury  Regulations  thereunder,  income,
gain, loss and deduction with respect to any property contributed to the capital
of the  Company  or which has been  adjusted  pursuant  to  Treasury  Regulation

                                       9



Section  1.704-1  (b)(2)(iv)(f)  shall,  solely  for  income  tax  purposes,  be
allocated  among the Members so as to take account of any variation  between the
adjusted  basis of such property to the Company for federal  income tax purposes
and its fair market  value  reflected  in the capital  accounts  initially or on
adjustment, as the case may be.

     (b) Any elections or other  decisions  relating to  allocations  under this
Section  3.3  shall  be made by the  Management  Committee  in any  manner  that
reasonably  reflects the purpose and  intention of this  Agreement.  Allocations
pursuant to this Section 3.3 are solely for purposes of federal, state and local
taxes and shall not affect,  or in any way be taken into  account in  computing,
any  Member's  Capital  Account  or share of  profits,  losses,  other  items or
distributions pursuant to any provision of this Agreement.

     3.4.  Fiscal  Year.  The  Fiscal  Year  of the  Company  for  both  tax and
accounting purposes (the "Fiscal Year") shall be the calendar year.

     3.5.  Partnership  for Tax  Purposes.  The  Members  hereby  agree that the
Company  shall be treated as a  partnership  for tax  purposes  under the United
States federal, state and local income tax laws or other laws, and further agree
not to take any position or to make any election,  in a tax return or otherwise,
inconsistent herewith,

     3.6. Tax Matters.  (a) The tax matters partner ("Tax Matters  Partner") for
purposes  of  Section  623 of the Code  shall  be  Progenics.  Unless  otherwise
required by law, the Tax Matters  Partner (i) shall not take any action pursuant
to this Section 3.6 unless such action has been  consented to by each Member and
(ii) shall  perform  all such  duties and  responsibilities  as directed by each
Member.

     (b) All  elections by the Company for income and franchise tax purposes and
all determinations regarding the book basis, depreciation or amortization of any
Company  assets,  and all other matters  relating to all tax returns  (including
amended returns),  including the  characterization  and allocation of income and
loss,  filed by the  Company,  including  tax audits  and  related  matters  and
controversies,  shall be made and  conducted  by the Tax Matters  Partner at the
expense of the Company,  subject to the approval of each Member. The Tax Matters
Partner shall, at the expense of the Company and subject to the approval of each
Member,  cause to be  prepared  and filed  all tax  returns  (including  amended
returns) required to be filed by the Company;  provided,  however,  that CYTOGEN
shall have the  opportunity to review any and all tax returns in advance of such
filing. In the event of a dispute between the Members concerning the preparation
and filing of the Company's tax returns,  the Members hereby agree to submit the
dispute  to  arbitration  to one of the  major  nationally-recognized  certified
public  accounting  firms,  whose  decision  on the  matter  shall be final  and
binding.

     (c) The Tax Matters  Partner shall be responsible  for all  negotiations on
behalf of the Company with the Internal  Revenue  Service or the  Departments of
the Treasury or Justice or any state or local tax authority  with respect to the
income tax  treatment of Company  items,  and shall provide each Member with the
opportunity,  at the  expense  of  the  Company,  to  participate  in  any  such

                                       10



negotiations.  The Tax Matters Partner shall not bind any Member to a settlement
agreement unless each Member has given its written consent to such agreement.

     3.7. Cash Flow Distributions.  Cash flow distributions of the Company shall
be made only after  payment of all  liabilities  and expenses of the Company and
establishment of reasonable  reserves.  Such distributions  shall be made to the
Members in accordance  with their  Percentages at such times and in such amounts
as determined by the  Management  Committee in its sole,  exclusive and complete
discretion.

     3.8.  Liquidating  Distributions Upon Dissolution.  Upon dissolution of the
Company, the remaining assets shall be applied as follows:

     (a) First,  to payment of the  liabilities  of the  Company  owing to third
parties  and then to  Members,  as  creditors.  After  payment of any such known
liabilities,  the Management  Committee shall set up such reasonable reserves as
it deems  reasonably  necessary for any contingent or unforeseen  liabilities or
obligations of the Company.  Such reserves  shall be held in a separate  account
for the  purpose of paying any such  contingent  or  unforeseen  liabilities  or
obligations,  and, at the expiration of such period as the Management  Committee
may deem  advisable,  such reserves shall be distributed to the Members or their
assigns in the manner set forth in Section 3.8(b) hereof.

     (b)  Second,  to the  Members  in  accordance  with their  Capital  Account
balances.  If such  distributions  are  insufficient to return to any Member the
full amount of its Capital  Account,  such Member shall have no recourse against
any other Member. If the Management Committee determines that the Company should
distribute any of its assets in kind, such assets shall,  except as set forth in
the following sentence, be distributed on the basis of their fair market values,
as determined by an appropriate  appraisal procedure as set forth or approved by
the  Management  Committee,  and the Capital  Accounts  of the Members  shall be
adjusted  prior to  liquidating  distributions  being  made to  reflect  how any
resulting  gain or loss would have been  allocated  under  Section 3.1 hereof if
such assets had been sold.  In the event of a dispute over the proper  valuation
of the Company's  in-kind  assets,  either Member shall have the right to submit
such dispute to arbitration in accordance with Section 10.2 hereof.  Each Member
shall have the right to require the Company to make the  distributions set forth
in this Section 3.8(b) first with any in-kind assets  contributed by such Member
to the  Company,  but only to the extent  such  distributions  do not exceed the
amount to which  such  Member  is  entitled  pursuant  to this  Section  3.8(b);
provided,  however,  that any and all  Intellectual  Property  transfers  from a
Member to the Company that were transferred without any value being reflected in
the  transferor's  Capital  Account  shall be  reconveyed  to the  transferor in
addition  to, and  without  diminishing,  any other  distributions  to which the
transferor shall be entitled. Upon the Company's dissolution, any and all rights
to other  Intellectual  Property,  developed or acquired by the Company prior to
its  dissolution  (such  Company  developments  and  acquisitions   collectively
referred to as the "Company  Inventions"),  shall be co-owned by  Progenics  and
CYTOGEN.

     3.9. Tax  Distributions.  To the extent that for any Fiscal Year the amount
of net income and gains of the  Company  allocated  to each  Member  exceeds the


                                       11



amount of losses of the  Company  allocated  to that  Member  for that and prior
Fiscal  Years  reduced  by the  amount of net  income  and gains of the  Company
allocated to the Members for prior Fiscal Years, the Management  Committee shall
use reasonable  efforts to cause the Company to distribute to each Member, as an
advance against the amounts thereafter  distributable to it pursuant to Sections
3.7 and 3.8,  no later than  April 1 of the  following  year,  an amount of cash
equal to (a) the amount  reasonably  calculated by the  Management  Committee to
equal the amount of the  federal,  state and local tax  liability on that excess
(based on the highest  individual or corporate  marginal federal income tax rate
for that year and the  percentage  with  respect  to state and local  income tax
rates for that year that the Management Committee determines appropriate),  less
(b) the aggregate  amount of prior  distributions  by the Company to that Member
for such Fiscal Year. No such distribution shall be made, however, to the extent
that  distributions  are  restricted  under the  terms of any note or  agreement
relating  to  borrowings  by the  Company or to the extent  that the  Management
Committee  determines  that  the  cash is  necessary  for the  operation  of the
business of the Company or for the  establishment  of reasonable  reserves or if
the Company would be rendered insolvent.  The Management Committee shall, to the
extent practical,  make  distributions  under this Section 3.9 annually based on
projections  of income.  If upon the  liquidation  of the Company the  aggregate
amount of  distributions  to any Member pursuant to this Section 3.9 exceeds the
aggregate  amount that would have been  distributed  to that Member  pursuant to
Sections  3.7 and 3.8 hereof (had there been no  distributions  pursuant to this
Section 3.9),  then that Member shall pay to the Company an amount equal to such
excess,  to be distributed  to the other Member in accordance  with Sections 3.7
and 3.8 hereof.

     3.10. Deficit Capital Account  Restoration.  Except as provided in the last
sentence of Section  3.9 hereof,  no Member  shall have any  obligation  to make
Additional Capital  Contributions to the Company in order to restore any deficit
Capital Account  balance upon  liquidation of the Company or liquidation of such
Member's Interest in the Company.

     3.11. Other Distributions.  Except as provided in this Agreement, no Member
shall be  entitled  to receive any  distribution  from the  Company  without the
consent of all other Members.



                                   ARTICLE IV
                                   MANAGEMENT

     4.1. Management Committee.  (a) Except as otherwise reserved to the Members
pursuant to this  Agreement,  the overall  management and control of the Company
shall  be  exercised  by  the  Members  through  a  committee  (the  "Management
Committee").  Except as determined by the Management  Committee pursuant to this
Article IV or  otherwise  pursuant to this  Agreement,  no Member shall have any
right or  authority  to take any action on behalf of the Company with respect to
third parties.

     (b) The Management  Committee  shall consist of four  individuals  (each, a
"Representative")  or  such  other  number  of  individuals  as  the  Management


                                       12



Committee  may,  from time to time  determine.  Of the  initial  members  of the
Management  Committee,  two shall be  appointed  by  Progenics  and two shall be
appointed by CYTOGEN.  The initial  Representatives of the Management  Committee
are:

                  Progenics:                [CONFIDENTIAL TREATMENT HAS BEEN
                                            REQUESTED]



                  CYTOGEN:                  [CONFIDENTIAL TREATMENT HAS BEEN
                                            REQUESTED]



Each Representative shall hold office until death, resignation or removal at the
pleasure of the Member which appointed such Representative.  If a vacancy occurs
on  the  Management   Committee,   the  Member  which   appointed  the  vacating
Representative shall appoint such Representative's successor.

     (c) Meetings of the Management Committee shall be held on two Business Days
(as defined  herein)  written notice (which may be waived and shall be deemed to
be waived by attendance at the meeting,  unless an individual objects,  prior to
or at the  beginning  of the  meeting,  to holding  the  meeting or  transacting
business  at  the  meeting).  Attendance  may  be in  person  or  by  conference
telephone.  Notwithstanding  the  number of  Representatives  on the  Management
Committee,  each Member's  Representatives  shall be required to vote as a block
("Voting  Block")  on behalf of such  Member.  The  Voting  Block of a  Member's
Representatives as of any given date shall equal such Member's  Percentage as of
such date. The Voting Blocks shall be automatically  adjusted upon any change in
Percentage of any appointing  Member.  Except as set forth in the next sentence,
the Management Committee shall act by vote of the Representative(s) whose Voting
Block constitutes more than  [CONFIDENTIAL  TREATMENT HAS BEEN REQUESTED] of the
aggregate Voting Blocks of all  Representatives,  at a meeting of the Management
Committee duly called and held.

     (i) All Major Decisions (as defined hereinafter) shall be made by a vote of
the  Representative(s)  whose Voting Block  constitutes more than  [CONFIDENTIAL
TREATMENT  HAS  BEEN   REQUESTED]   of  the  aggregate   Voting  Blocks  of  all
Representatives  (a  "Supermajority  Vote").  A "Major Decision" means decisions
concerning  the  merger or  consolidation  of the  Company or the sale of all or
substantially all of the Company's assets.

     (ii)  The  vote of each  Member  shall  be cast by such  Member's  Managing
Representative (as defined  hereinafter).  The Management Committee may also act
by unanimous written consent of the Representatives.  The Representatives  shall
not be  compensated  for  their  services  as such,  but  shall be  entitled  to
indemnification  by the Company in  accordance  with  Section  4.3  hereof.  Any
Deadlock (as defined  hereinafter) of the Management Committee shall be resolved
pursuant to Section 4.1(f) hereof.

                                       13


     (d) Any  Representative  on the Management  Committee (or alternatively the
Member who appointed such Representative) may appoint another  Representative on
the Management Committee to act for him or her, and the Management Committee may
delegate in writing,  to any of the  Representatives  or to any Member or to any
other agent such  authority  to act on its behalf or on behalf of the Company as
it shall deem appropriate.

     (e) Subject to the other  provisions of this Agreement and the requirements
of applicable law, the Management  Committee  shall have the full,  complete and
exclusive power and discretion to take all action that it considers necessary or
desirable in connection with the management of the Company, and may exercise, on
behalf of the Company,  all of the powers of a limited  liability  company under
the Act including, without limitation, the following powers:

     (i) to enter into contracts or agreements of any kind,  including  selling,
leasing, conveying, licensing, exchanging or otherwise transferring or disposing
of any  Company  property  or  assets,  as well as  contracts  of  guaranty  and
suretyship  with  any  person  including  with  any  Member,  Representative  or
affiliate of either of them without the vote of the Members;

     (ii)  to  determine  the   strategies   and  methods  for   developing  and
commercializing  products and for exploiting the intellectual property rights of
the Company;

     (iii) to establish and  maintain,  or cause to be  maintained,  the Capital
Accounts  of the Members and the books and records of the Company as required by
law and by this Agreement;

     (iv) to appoint such  Officers (as defined  hereinafter)  of the Company as
the Management Committee determines desirable, and such Officers of the Company:

          (1) need not be members or Representatives;

          (2) shall have the powers and duties  delegated  to them by the
Management Committee; and

          (3) shall serve at the pleasure of the Management Committee;.

     (v) to employ and dismiss  attorneys,  accountants,  independent  auditors,
custodians,  brokers and such other  advisers or agents in  connection  with any
matter relating to the business of the Company  (including,  without limitation,
the  Representatives on the Management  Committee or persons or firms affiliated
with them) and to make payment for such  services and other  expenses out of the
funds of the Company;

     (vi) to open, maintain and close bank accounts for the Company;

                                       14

     (vii) to sign checks of the Company;

     (viii) to admit additional members to the Company;

     (ix) to call meetings of the Members of the Company;

     (x) to declare and make distributions;

     (xi) to permit, require or prohibit withdrawals of capital from and Capital
Contributions to the Company;

     (xii) to hold part of the assets of the Company in cash  without  liability
for  interest  or the  payment  of  expenses  or  the  making  of  distributions
therewith;

     (xiii) to determine the  accounting  period or accounting  periods to which
any  income,  gain,  obligation,  loss,  liability,   deduction  or  expense  is
attributable;

     (xiv) to prepare,  execute and file tax returns or information  returns for
the Company and to make tax elections as they deem  appropriate,  subject to the
provisions of Section 3.6 hereof;

     (xv) to incur indebtedness for any purpose;

     (xvi)  to  make  loans,   including  loans  to  Members,   and  to  provide
indemnification  or  guarantee  the  indebtedness  and  obligations  of  others,
including Members;

     (xvii) to settle, compromise,  assign, pledge, transfer, release, submit to
arbitration,  or stipulate to  judgment,  or consent to do the same,  any claim,
suit, demand or judgment against the Company;

     (xviii) to delegate authority to subcommittees,  Members,  Representatives,
Officers or other  parties to take  actions on behalf of the Company  consistent
with the  terms of this  Agreement  and to  execute  documents  on behalf of the
Company in connection therewith; and

     (xix) to bring,  threaten to bring or prosecute,  on behalf of the Company,
any claim in a judicial proceeding or arbitration forum.

     (f) If, at any time the vote of the  Representatives  required  to  approve
action  with  respect  to a  particular  matter  has  not  been  obtained  after
comprehensive discussion between the Representatives, and such failure to obtain
the  requisite  vote impedes in any material  respect the  Company's  ability to
continue its business (the  "Deadlock"),  the Deadlock  shall first be submitted
(the "Submission") by the Management  Committee (but if the Management Committee
cannot agree on the form or substance of the  Submission,  the Submission may be
made by any  Representative) to the Chief Executive Officer of Progenics and the


                                       15


Chief Executive Officer of CYTOGEN for review and discussion. Such persons shall
meet as soon as possible after the Submission is given,  and in any event within
ten calendar  days,  and endeavor in good faith to resolve the matter.  If these
officers do not,  within ten calendar  days after they first meet,  or within 20
calendar days after the  Submission is given,  mutually  resolve the Deadlock or
agree on a method of resolving  the Deadlock,  either Member may,  within the 30
calendar  day period  following  such 20  calendar  days after  delivery  of the
Submission,  by written  notice  given to the other  Member  within  such 30 day
period,  cause the Deadlock to be submitted to  arbitration  pursuant to Section
10.2 hereof.

     (g) (i) If submission of a Deadlock to the procedures  described in Section
4.1(f) does not,  within the time periods  specified in Section  4.1(f)  hereof,
result in resolution of the Deadlock,  submission of the Deadlock to arbitration
or  agreement by the Members on an  alternative  dispute  resolution  procedure,
either party may elect to exercise the buy/sell right  contained in this Section
4.1(g) (the  "Buy/Sell  Right").  The Member  electing to exercise  the Buy/Sell
Right  (the  "Offeror")  shall  furnish  in  writing  to the other  Member  (the
"Offeree") the Offeror's irrevocable,  unconditional (except as provided herein)
and  binding  offer  (such  notice  being  referred  to herein as the  "Exercise
Notice") to purchase the Offeree's  Interest or to sell the  Offeror's  Interest
for a cash  purchase  price  determined in  accordance  with Section  4.1(g)(ii)
hereof (the  "Purchase  Price").  The Exercise  Notice shall set forth an amount
expressed in dollars and without  contingencies (the "Valuation"),  which amount
shall be used to calculate,  in accordance with Section  4.1(g)(ii)  hereof, the
Purchase Price.  The Valuation is intended to represent the amount that would be
payable for 100% of the Interests of the Company.  Within 15 calendar days after
the Exercise Notice is given,  the Offeree may give notice to the Offeror of its
irrevocable,  unconditional  (except as provided  herein)  and binding  election
either:

     (1) to  purchase  the entire  Interest of the Offeror for an amount in cash
equal to the Purchase Price; or

     (2) to sell its entire  Interest to the Offeror for an amount in cash equal
to the Purchase Price.

Failure of the Offeree to give  notice of its  decision  within such  applicable
time period shall  constitute  a conclusive  election by the Offeree to sell its
entire Interest pursuant to this Section 4.1(g)(i).

     (ii)  The  Purchase  Price  shall  be  equal  to  the  seller's  Percentage
multiplied by the Valuation.

     (iii) Subject to the provisions of Section 4.1(g)(iv) hereof, a transfer of
Interests  pursuant to this  Section  4.1(g) shall take place at a closing to be
held on a day other than Saturday,  Sunday or any other day on which  commercial
banks  located  in New York,  New York are  authorized  by law to be closed  for
business  ("Business  Day").  Such date shall be  selected by and set forth in a
notice by the  Offeror  given  promptly  after the Offeree  gives  notice of its
election under Section 4.1(g)(i)  hereof,  which date shall be at least ten days
but prior to 20 days  after the  Offeree  gives  notice  of its  election  under
Section 4.1(g)(i), at such location in New York, New York as the Offeror selects

                                       16


or as otherwise agreed to by the parties.  In such notice, the purchasing Member
shall  additionally  specify  whether the  purchase  will be by the Member,  the
Company, a combination of the Company and the Member,  and/or the designee(s) of
the  Company  and/or the  designee(s)  of the Member (the  "Purchaser").  At the
closing,  the Purchase Price  specified  above shall be paid by the Purchaser by
wire transfer of immediately available federal funds to an account designated by
the selling Member.  The terms of the purchase and sale shall be  unconditional,
except that the selling Member shall represent and warrant to the Purchaser that
its  Interest  in the Company is not  subject to any legal or  equitable  claims
(other than legal or equitable claims to such Interest, if any, of the Purchaser
pursuant  to this  Agreement)  and shall  deliver at the  closing an  instrument
confirming such  representation and warranty.  In addition,  the Purchaser shall
represent  and warrant to the selling  Member that it has the full right,  power
and  authority to  effectuate  the purchase and upon demand shall deliver at the
closing an instrument confirming such representation and warranty. Upon the sale
of a Member's  Interest in the  Company  pursuant to this  Section  4.1(g),  the
selling Member's appointed Representatives shall be deemed to have automatically
resigned from the Management Committee.

     (iv) The  closing  date set forth in Section  4.1(g)(iii)  hereof  shall be
postponed if any required  regulatory filings have not been made or any required
consents or approvals  (regulatory or otherwise)  have not been received by such
closing  date,  but only until such filings have been made or such consents have
been received and, if applicable, until the expiration or earlier termination of
the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements
Act of 1976, as amended (the "HSR Act").  The Members  hereby agree to use their
reasonable  best  efforts  and to  cooperate  with each other to effect any such
required  regulatory  filings,  including but not limited to, a filing under the
HSR Act, if applicable,  and to obtain any such required  consents or approvals,
in order to close a transfer of Interests pursuant to this Section 4.1(g).

     (v) The consummation of any purchase or sale of Interests  pursuant to this
Section 4.1(g) shall be subject to the satisfaction of the provisions of Section
6.2 hereof.

     (h) Each of Progenics and CYTOGEN shall appoint one managing Representative
(the  "Managing  Representative")  from  the  Representatives.  Every  contract,
agreement,  certificate,  document or other instrument executed by both Managing
Representatives  shall be conclusive  evidence in favor of every person  relying
thereon or claiming  thereunder that, at the time of the delivery  thereof,  (1)
the Company was in  existence,  (2) this  Agreement  had not been  terminated or
canceled or amended in any manner so as to restrict  such  authority  (except as
shown in any  instrument  duly filed  under the Act) and (3) the  execution  and
delivery  thereof was duly  authorized by the Management  Committee.  Any person
dealing  with the  Company or the  Management  Committee  may,  until and unless
subsequently  notified by both Managing  Representatives,  rely on a certificate
signed by both Managing Representatives hereunder:

     (i)  as  to  who  are  the  Representatives  and  Managing  Representatives
hereunder;


                                       17



     (ii)  as to the  existence  or  nonexistence  of any  fact or  facts  which
constitute  conditions  precedent to acts by the Management  Committee or are in
any other manner germane to the affairs of the Company;

     (iii) as to who is  authorized  to  execute  and  deliver  any  instrument,
contract, agreement, certificate or document for the Company;

     (iv) as to the  authenticity  of any copy of this  Agreement and amendments
thereto; or

     (v) as to any  act or  failure  to act by the  Company  or as to any  other
matter whatsoever involving the Company.

     (i) The  Management  Committee  shall  establish an  Intellectual  Property
subcommittee,  composed of such  members of the  Management  Committee,  or such
other persons, as the Management Committee may determine and with such authority
as may be delegated  thereto.  The  Intellectual  Property  Committee shall have
responsibility for establishing and implementing,  in consultation with counsel,
the Company's strategies for creating and/or maintaining its patent estate.

     4.2. Meetings of Members.  The Members shall meet on such periodic basis as
the Management Committee may determine. Special meetings of the Members, for any
purpose or purposes,  may be called by the Management Committee or by any Member
of the Company.  All meetings shall be held at the Company's  principal place of
business or at any other place  designated  by the  Management  Committee,  and,
unless  otherwise  prohibited  by law, may be  conducted by means of  conference
telephone  or  similar  communication   equipment,  in  the  discretion  of  the
Management  Committee.  Not less than two Business Days before each meeting, the
Management  Committee  shall give  written  notice of the meeting to each Member
entitled to vote at the meeting.  The notice shall state the place,  date,  hour
and purpose of the  meeting.  Notwithstanding  the  foregoing  provisions,  each
Member who is entitled to notice  shall be deemed to have waived  notice if such
Member  attends the  meeting,  unless such  Member  objects,  prior to or at the
beginning of the meeting, to holding the meeting or transacting  business at the
meeting.  At any such meeting of Members,  the presence in person or by proxy of
the Members  holding an  aggregate  of a majority  in  Interests  constitutes  a
quorum.  A member may vote either in person or by written  proxy signed by or on
behalf  of the  Member  or by or on  behalf  of  the  Member's  duly  authorized
attorney-in-fact.

In lieu of holding a meeting,  the Members may vote or otherwise  take action by
the unanimous written consent of the Members.

     4.3.  Liability and  Indemnification.  (a) Except as otherwise  provided by
law, none of the  Representatives,  any Officer or any Member  designated by the
Management Committee to act on its behalf (or any officer, director, employee or
affiliate of any such Member),  in each case acting in such  capacity,  shall be
liable,  responsible  or  accountable in any way for damages or otherwise to the
Company or to any of the Members  for (a) any act or failure to act  pursuant to
this  Agreement  or  otherwise  if (i) such person  acted in good faith and in a



                                       18


manner it reasonably  believed to be in, or not opposed to, the interests of the
Company,  (ii) the conduct of such person did not constitute  gross  negligence,
fraud, bad faith, intentional misconduct or a knowing violation of law and (iii)
such person did not gain a financial  benefit to which he or she was not legally
entitled,  or (b) any  losses  due to the  negligence  or  unauthorized  acts of
advisers, consultants or other agents of the Company.

     (b)  The  Company   shall   indemnify,   defend  and  hold   harmless  each
Representative,  each Officer and any Member  designated to act on behalf of the
Management Committee (and any officer,  director,  employee and affiliate of any
such Member),  in each case acting in such capacity (an  "Indemnified  Person"),
from and against any claims, losses,  liabilities,  damages,  fines,  penalties,
costs  and  expenses  (including,   without  limitation,   reasonable  fees  and
disbursements  of  counsel  and  other  professionals)  arising  out  of  or  in
connection  with any act or failure to act by an Indemnified  Person pursuant to
this Agreement, or the business and affairs of the Company;  provided,  however,
that an Indemnified Person shall not be entitled to indemnification hereunder if
it is  judicially  determined  that (a) such  Indemnified  Person's  actions  or
omissions to act were (i) made in bad faith,  (ii) constituted gross negligence,
fraud,  intentional  misconduct or a knowing violation of law, or (iii) were the
result of active  and  deliberate  dishonesty,  or (b) such  Indemnified  Person
personally  gained a  financial  benefit  to which  Indemnified  Person  was not
legally entitled.

     4.4.  Duties,  Right to Conduct Other Business.  (a) To the extent that, at
law or in equity, a Member (or any officer, director or employee of such Member)
has duties (including  fiduciary duties) and liabilities relating thereto to the
Company or to the Members, (i) the Member (or any officer,  director or employee
of any Member) acting under this  Agreement or otherwise  shall not be liable to
the Company or to any Member for its good faith  reliance on the  provisions  of
this Agreement, and (ii) such Member's duties and liabilities (or the duties and
liabilities of any officer,  director or employee of any Member) may be expanded
or restricted by the provisions of this Agreement.

     (b) For so long as Progenics and CYTOGEN are Members of the Company and for
a period of three years thereafter  (unless the Company  liquidates  pursuant to
Article VII hereof),  neither Progenics nor CYTOGEN will engage, either directly
or  indirectly,  in  the  research,  development,  manufacturing,  marketing  or
commercialization  of products  in the Field  except for the benefit of the LLC.
Notwithstanding  the foregoing,  this Agreement  shall not preclude or limit, in
any respect, the rights of Progenics and CYTOGEN to engage in activities outside
of the Field,  whether or not such activities are competitive with activities of
the Company,  and neither  Progenics  nor CYTOGEN  shall have any  obligation to
offer such business activities to the Company.

     (c) For so long as Progenics and CYTOGEN are Members of the Company and for
a period of three years thereafter  (unless the Company  liquidates  pursuant to
Article VII hereof),  neither  Progenics nor CYTOGEN shall solicit or induce any
person who is employed by or who is a consultant  to or is otherwise  affiliated
with the Company to terminate his or her employment,  consultancy or affiliation
with the Company. In addition,  for so long as Progenics and CYTOGEN are Members

                                       19


of the Company and for a period of three years thereafter, neither Progenics nor
CYTOGEN  shall  solicit  or induce any  person  who is  employed  by or who is a
consultant to or otherwise  affiliated with the other Member to terminate his or
her employment, consultancy or affiliation with the other Member.

     4.5.  Scientific   Advisory  Board.  The  Management   Committee  shall  be
authorized to establish a Scientific  Advisory Board (the "SAB").  The SAB shall
be composed of such  scientific or other  personnel as the Management  Committee
deems  advisable  and may include as members  employees and  consultants  of the
Company as well as persons  otherwise  unaffiliated  with the  Company.  The SAB
shall meet at such places and at such times as shall be determined as advisable.
The Management  Committee may authorize  compensation  for members of the SAB in
such amounts and under such terms as the Management Committee may determine.

     4.6. Research Grants.  Neither Progenics nor CYTOGEN shall, so long as such
person is a member of the  Company,  apply to any funding  source for a Research
Grant in the  Field  unless  such  application  is made for the  benefit  of the
Company.

                                   ARTICLE V
                                    OFFICERS

     5.1.  Designation,  Authority and Compensation of Officers.  The Management
Committee may delegate such of its authority as it deems  advisable from time to
time to officers of the Company, including, without limitation, a president, one
or more vice-presidents and/or a secretary/treasurer (an "Officer").  The title,
extent of  authority,  term of office and  compensation  of any Officer shall be
determined by the Management Committee in its sole discretion.

     5.2.  Tenure of  Officers.  The  Officers of the Company  shall hold office
until  their  successors  are chosen and  qualify,  unless a  different  term is
specified by the Management  Committee in appointing  the Officer,  or until the
Officer's  earlier  death,  resignation  or removal.  Any Officer  chosen by the
Management Committee may be removed at any time by the Management Committee,  in
its sole  discretion,  and any vacancy  occurring in any office may be filled by
the  Management  Committee,  in its sole  discretion.  Any Officer may resign by
delivering his or her written  resignation to the Company at its principal place
of  business.  Such  resignation  shall be effective  upon receipt  unless it is
specified to be effective at some other time or upon the happening of some other
event.

                                   ARTICLE VI
          TRANSFER OF INTERESTS, WITHDRAWAL AND TERMINATION OF MEMBERS

     6.1. Transfer or Withdrawal Prohibited;  Change of Control of a Member. (a)
Except as expressly  provided herein, no Member may withdraw from the Company or
sell,  assign,  transfer,  pledge,  hypothecate,  mortgage  or create a security
interest,  directly  or  indirectly  ("Transfer"),  in all or any portion of its


                                       20


Interest  without the prior written consent of the Management  Committee,  which
consent may be withheld in the sole and absolute  discretion  of the  Management
Committee.  Any  purported  withdrawal  or  Transfer  of an Interest by a Member
without the requisite consent in writing shall be null and void, and the Company
shall be  entitled  to damages as a result of,  and/or  injunctive  relief  with
respect to, any attempts to withdraw or Transfer.

     (b) In the event that the Management  Committee consents to a Transfer of a
Member's  Interest,  such consent shall,  unless expressly stated otherwise,  be
deemed a consent only to the  assignment of such Member's  economic  interest in
profits,  losses  and  distributions  and shall  not be deemed a consent  to the
admission of such  assignee as a member of the Company as a  substitute  for the
assignor,  and such assignee shall not have any of the rights of a member of the
Company, including,  without limitation,  voting rights, unless otherwise stated
in writing by the Management Committee. Except to the extent that the Management
Committee  has  consented  to the  admission  of the assignee as a member in the
Company and/or  consented to the exercise of voting rights by the assignee,  the
assigning  Member  shall  retain  all  voting  rights  in  connection  with  the
transferred Interest.

     (c) In the event  that at any time  there  occurs a Change of  Control  (as
hereinafter  defined) of a Member,  such Member's  Interest shall  automatically
convert into an economic interest only in the profits,  losses and distributions
of the  Company,  and such Member shall not have any other rights of a member of
the Company,  including,  without  limitation,  voting and marketing rights. For
purposes hereof, a "Change in Control" shall be deemed to have occurred:  (i) on
the sale or other disposition of all or substantially all of the Member's assets
to any  entity,  person or related  group of  persons;  (ii) when there shall be
consummated  any  consolidation,  merger,  reorganization  or similar  corporate
transaction (a "Corporate Transaction") of the Member (A) in which the Member is
not the  continuing or surviving  entity (other than a  consolidation  or merger
with a wholly owned subsidiary of the Member in which all shares of common stock
of such Member  outstanding  immediately prior to the effectiveness  thereof are
changed into or exchanged for the same  consideration)  or (B) pursuant to which
the common  stock of such Member  would be converted  into cash,  securities  or
other  property,  in each case,  other than a  Corporate  Transaction  that is a
Qualifying  Corporate  Transaction (as defined below); (iii) when any person, or
any persons  acting  together  which would  constitute a "group" for purposes of
Section 13(d) of the Securities Exchange Act of 1934, as amended,  together with
any affiliates  thereof,  shall beneficially own (as defined in Rule 13d-3 under
the  Exchange  Act) at least 50% of the total  voting  power of all  classes  of
capital  stock of the Member  entitled  to vote  generally  in the  election  of
directors of the Member  (unless the  "acquisition"  is deemed to have  occurred
indirectly solely as a result of the completion of a Corporate  Transaction that
is not a Change in Control pursuant to clause (ii) above); (iv) when at any time
during any consecutive two-year period, individuals who at the beginning of such
period  constituted the Board of Directors of the Member  (together with any new
directors  whose  election by such Board of  Directors or whose  nomination  for
election by the  stockholders of the Member was approved by a vote of 75% of the
directors  then still in office who were either  directors  at the  beginning of
such period or whose  election or  nomination  for  election was  previously  so
approved)  cease  for any  reason  to  constitute  a  majority  of the  Board of


                                       21

Directors of the Member then in office;  or (v) when the Member is liquidated or
dissolved  or  adopts  a plan  of  liquidation  or  dissolution.  A  "Qualifying
Corporate  Transaction" shall be any Corporate  Transaction in which the holders
of common stock of the Member  immediately  prior to such Corporate  Transaction
have, directly or indirectly,  at least (i) a majority of the total voting power
of all classes of capital  stock  entitled to vote  generally in the election of
directors of the continuing or surviving entity immediately after such Corporate
Transaction in  substantially  the same  proportion as their ownership of common
stock  before  such  transaction  or (ii) 25% of the total  voting  power of all
classes of capital stock entitled to vote generally in the election of directors
of  the  continuing  or  surviving  entity   immediately  after  such  Corporate
Transaction in  substantially  the same  proportion as their ownership of common
stock before such  transaction  and, in the case of this clause (ii),  the other
Member has given a CIC Approval.  A "CIC  Approval"  shall be given by the other
Member if such  Member  cannot  conclude  in good  faith  and in its  reasonable
judgment after  discussions  with the parties to the Corporate  Transaction that
such Corporate  Transaction and any resulting change in management or leadership
is reasonably  likely to disrupt or delay the  commercialization  of products by
the LLC, or fundamentally  alter the approach,  philosophy or vision of the LLC,
giving due regard to the importance of good-faith  cooperation and collaboration
and  single-mindedness of purpose between CYTOGEN and Progenics which has formed
the basis for the collaboration  initially contemplated by the parties hereto. A
CIC Approval may not be unreasonably  withheld,  and failure of the other Member
to give a CIC Approval may be  contested in  arbitration  pursuant to Article 10
hereof. Notwithstanding the foregoing, a Change of Control shall not include any
transaction  the  purpose  of  which is to  reorganize  the  Member's  corporate
structure,  reincorporate  the Member in another  jurisdiction  or undertake any
other action which does not have the purpose or effect of  materially  affecting
the ownership and/or control of the Member at the time of such transaction.


     6.2. Regulatory  Matters.  Anything in this Article VI or elsewhere in this
Agreement to the contrary notwithstanding,  no assignment, transfer, encumbrance
or other  disposition of all or any part of any Member's  Interest shall be made
or  shall  be  effective  unless  (a)  prior to the  consummation  thereof,  all
assignees and transferees with respect thereto shall have made to the Company in
writing all of the  representations  required by the  Management  Committee,  to
ensure compliance with applicable  securities and other laws and (b) if required
by the  Management  Committee,  the Company is  provided  with an opinion of its
legal counsel,  or other legal counsel  satisfactory  to the Company's  counsel,
stating that (i) such assignment, transfer, encumbrances or other disposition is
exempt from the Securities Act of 1933, as amended, and is permissible under all
other  applicable  federal and state  securities  laws without  registration  or
qualification  of any  security  or any person and (ii) the  transaction  is not
prohibited  under,  and does not conflict with, such other federal or state laws
as the Management Committee may specify.

     6.3. Default;  Buyout/Liquidation  Option. (a) A Member shall be in default
("Defaulting  Member")  under this  Agreement  upon the occurrence of any of the
following events ("Default"):


                                       22

     (i) the  Bankruptcy (as defined  hereinafter)  or dissolution of the Member
(the Bankruptcy or dissolution of the Member shall hereinafter be referred to as
the  "Dissolution"),  in which event such Member  shall  immediately  notify the
other Member  ("Other  Member") and the Company in writing of the  occurrence of
such Dissolution.

As used herein, the term "Bankruptcy" shall mean:

     (1) A  Member  files  a  voluntary  petition  in  bankruptcy  or  shall  be
adjudicated  a bankrupt or  insolvent,  or shall file any  petition or answer or
consent  seeking any  reorganization,  arrangement,  composition,  readjustment,
liquidation or similar relief for itself under the present or future  applicable
federal,  state or other  statute or law relating to  bankruptcy,  insolvency or
other  relief for  debtors,  or shall seek or  consent  to or  acquiesce  in the
appointment of any trustee,  receiver,  conservator or liquidator of said Member
of all or any  substantial  part of its  properties  or its  Interest  (the term
"acquiesce" as used in this  definition  includes the failure to file a petition
or motion to vacate or discharge any order, judgment or decree);

     (2) A court of competent  jurisdiction enters an order,  judgment or decree
approving  a  petition  filed  against  any  Member  seeking  a  reorganization,
arrangement,  composition,  readjustment,  liquidation,  dissolution  or similar
relief  under the  present or any future  federal  bankruptcy  act, or any other
present or future applicable federal,  state or other statute or law relating to
bankruptcy,  insolvency  or other  relief for  debtors,  and such  Member  shall
acquiesce in the entry of such order, judgment or decree or such order, judgment
or decree  shall remain  unvacated  and unstayed for an aggregate of 60 calendar
days  (whether  or not  consecutive)  from  the date of  entry  thereof,  or any
trustee,  receiver,  conservator  or  liquidator of such Member or of all or any
substantial  part of its properties or its Interest  shall be appointed  without
the consent or acquiescence of such Member,  and such  appointment  shall remain
unvacated  and unstayed for an  aggregate  of 60 calendar  days  (whether or not
consecutive);

     (3) A Member  admits  in  writing  its  inability  to pay its debts as they
mature; or

     (4) A Member  makes an  assignment  for the benefit of  creditors  or takes
other similar action for the protection or benefit of creditors.

     (ii) the Member has breached in any material  respect this  Agreement,  the
PSMA/PSMP License Agreement or the Services Agreement, which breach has not been
cured within 60 calendar days after the  Management  Committee or  non-breaching
Member has given a written notice to the breaching  Member stating that a breach
has occurred  and  identifying  in  reasonable  detail the  relevant  facts with
respect to such breach.

     (iii) on two occasions, an arbitrator determines that a Member has acted in
bad faith in refusing to approve a Budget pursuant to Section 2.4(b).


                                       23



     (iv) so long as Progenics  and CYTOGEN are the only Members of the Company,
the Member's Percentage falls below [CONFIDENTIAL  TREATMENT HAS BEEN REQUESTED]
("Nonconforming  Percentage"), in which event (provided that at such time as any
Member's  Percentage  shall be reduced to zero,  such Member shall cease to be a
member in the Company) the Management  Committee  shall  immediately  notify all
Members in writing of the Nonconforming  Percentage.  Subsequently,  any further
reduction in such Member's  Percentage shall constitute a separate Default again
giving rise to the options under Section 6.3(b) hereof.

The Management  Committee  shall promptly (but in any event within five Business
Days) give notice (a "Default  Notice") to the Members of any Default under this
Section 6.3(a) of which it becomes aware.  The Other Member shall be entitled to
give the Default  Notice to the  Defaulting  Member on behalf of the  Management
Committee. In any event, failure to provide notice to the Defaulting Member does
not constitute a waiver of the default.

     (b) Upon the occurrence of a Default and the giving of the Default  Notice,
in each case as described in Section  6.3(a)  hereof,  (i) all marketing  rights
held by the  Defaulting  Party  under  Article  IX  hereof,  and all  rights  of
Progenics (if Progenics is the Defaulting  Party) under Section 2.2(d) hereof to
direct the application of the Progenics R&D Capital Contributions and to conduct
the research and development  program  contemplated  by the Services  Agreement,
shall  terminate and (ii) an option to purchase all but not less than all of the
Interest  of the  Defaulting  Member  shall  arise  immediately  in favor of the
Company  and/or the Other Member.  The  determination  as to whether the Company
will  exercise the purchase  option  shall be made by the Other  Member.  If the
purchase option is not exercised  within 45 calendar days from the giving of the
Default  Notice,  the Other Member may, but shall not be required to,  within 90
calendar  days from the giving of the  Default  Notice,  cause the Company to be
dissolved and liquidated pursuant to Article VII hereof.

     (c)  The  purchase  option  arising  under  Section  6.3(b)  hereof  may be
exercised  only by  giving a  written  notice  to the  Defaulting  Member of the
election to exercise such purchase option within the 45 calendar day time period
specified in Section 6.3(b) hereof (the "Exercise Notice").

     (d) If the Company  and/or the Other Member  exercises the purchase  option
arising under Section 6.3(b) hereof,  the purchase  price  determination  of the
Defaulting  Member's  Interest  shall  first  be  submitted  by  the  Management
Committee  to the  Chief  Executive  Officer  of  each  Member  for  review  and
discussion.  Such  persons  shall meet as soon as  possible  after the  Exercise
Notice is given, and in any event within ten calendar days, and endeavor in good
faith to determine  the purchase  price.  If these  officers do not,  within ten
calendar  days after  they  first  meet,  or within 20  calendar  days after the
Exercise  Notice  is  given,  mutually  agree  upon a  purchase  price  for  the
Defaulting  Member's  Interest,  either  Member may,  within the 30 calendar day
period following such 20 calendar days after delivery of the Exercise Notice, by
written  notice given to the other Member  within such 30 day period,  cause the
purchase price determination of the Defaulting Member's Interest to be submitted


                                       24


to  arbitration  pursuant to Section 10.2  hereof.  In the event such dispute is
submitted  to  arbitration,  the  purchase  price  for the  Defaulting  Member's
Interest shall be calculated by the  arbitrator by multiplying  the total entity
value  of the  Company  (as  determined  by the  arbitrator)  by the  Defaulting
Member's Percentage.  In the event the Company and/or the Other Member exercises
the purchase  option,  the Company  and/or the Other  Member and the  Defaulting
Member  shall be  obligated to  consummate  the  purchase at the purchase  price
determined in the manner described above.

     (e) (i) Subject to the provisions of Section  6.3(e)(ii) hereof, a transfer
of  Interests  pursuant to this  Section 6.3 shall take place at a closing to be
held on a Business Day at least ten calendar  days but prior to 20 calendar days
after  the  determination  of the  purchase  price  of the  Defaulting  Member's
Interest  pursuant to Section 6.3(d)  hereof,  which date shall be determined by
mutual  agreement of the Members,  or if no agreement can be reached,  on a date
unilaterally set by the Company and/or the Other Member, at such location in New
York,  New York as the Company  and/or the Other Member  selects or as otherwise
agreed to by the parties.  In the Exercise Notice,  the Company and/or the Other
Member shall  additionally  specify  whether the  purchase  will be by the Other
Member, the Company,  a combination of the Company and the Other Member,  and/or
the  designee(s) of the Company and/or the  designee(s) of the Other Member (the
"Purchasing  Party(ies)").  At the closing,  the purchase price  specified above
shall be paid by the  Purchasing  Party(ies)  by wire  transfer  of  immediately
available federal funds to an account  designated by the Defaulting  Member. The
term of the purchase and sale shall be unconditional, except that the Defaulting
Member shall be deemed to  represent  and warrant to the  Purchasing  Party(ies)
that its Interest is subject to no legal or equitable  claims  (other than legal
or  equitable  claims to such  Interest,  if any, of the  Purchasing  Party(ies)
pursuant  to this  Agreement)  and shall  deliver at the  closing an  instrument
confirming  such  representation  and  warranty.  In  addition,  the  Purchasing
Party(ies) shall represent and warrant to the Defaulting  Member that it has the
full right, power and authority to effectuate the purchase and upon demand shall
deliver  at  the  closing  an  instrument  confirming  such  representation  and
warranty. Upon the sale of a Member's Interest pursuant to this Section 6.3, the
Member's  appointed  Representatives  shall  be  deemed  to  have  automatically
resigned from the Management Committee.

     (ii) The  closing  date set  forth in  Section  6.3(e)(i)  hereof  shall be
postponed if any required  regulatory filings have not been made or any required
consents or approvals  (regulatory or otherwise)  have not been received by such
closing  date,  but only until such filings have been made or such consents have
been received and, if applicable, until the expiration or earlier termination of
the applicable waiting period under the HSR Act. The Members hereby agree to use
their  reasonable  best efforts and to  cooperate  with each other to effect any
such required regulatory  filings,  including but not limited to, a filing under
the HSR Act,  if  applicable,  and to  obtain  any  such  required  consents  or
approvals,  in order to close a transfer of  Interests  pursuant to this Section
6.3.

     (f) The consummation of any purchase or sale of Interests  pursuant to this
Section 6.3 shall be subject to the  satisfaction  of the  provisions of Section
6.2 hereof.


                                       25

     (g) A Defaulting Member shall be liable to the Company and the Other Member
for all damages  arising out of a Default and any other  amounts the  Defaulting
Member owes to the Company or Other  Member  pursuant to this  Agreement  or any
other  agreement,  and any such amounts may be offset against any other payments
otherwise due from the Purchasing Party(ies) to the Defaulting Member hereunder.
Exercise or failure to exercise any of the options  pursuant to this Section 6.3
shall not relieve the Defaulting  Member of the  liabilities  arising out of the
Default.

                                  ARTICLE VII
             DISSOLUTION, LIQUIDATION AND TERMINATION OF THE COMPANY

     7.1. Events of  Dissolution.  The Company shall be dissolved and liquidated
upon the first to occur of the following events:

     (a) Upon the unanimous written consent of the Management Committee.

     (b) Upon the termination of the Company's  business as a result of the sale
by the Company of all or substantially all of its business and assets.

     (c) Upon the Other Member's exercise of its right to dissolve and liquidate
the Company under Section 6.3 hereof.

     7.2. Procedure for Winding Up and Dissolution. If the Company is dissolved,
the Management  Committee shall wind up its affairs  pursuant to the appropriate
provisions  of the Act. On winding up of the Company,  the assets of the Company
shall be distributed in accordance with Section 3.8 hereof.

     7.3. Termination of Company. Upon the completion of the liquidation of' the
Company and the distribution of all Company assets,  the Company's affairs shall
terminate and the Management  Committee  shall execute and file a certificate of
cancellation  of the  Company's  Certificate,  as  well  as any  and  all  other
documents required to effect the termination of the Company under the Act.

     7.4. License Grants on Dissolution.  Upon dissolution of the Company,  each
Member (in each case, the "Grantee Member") shall be granted, at its request, by
the other Member (the "Grantor Member") a non-exclusive  license, with the right
to sublicense, for use in the Field to any Intellectual Property rights in which
the Grantor Member has a licensable right ("Grantor  Rights") to the extent that
the development and commercialization of any product or service that includes or
embodies  a  Company  Invention  (including  developing,  making,  having  made,
distributing,  using,  offering for sale,  selling,  having sold,  importing and
exporting such products and services) would in the absence of such non-exclusive
license,  infringe or conflict with such Grantor Rights. Royalties in respect of
such non-exclusive  license shall be payable at cost (calculated as described in
Section 5 of the  PSMA/PSMP  License  Agreement,  and including any milestone or
other  payments  required  to be  paid to any  licensor  of the  Grantor  Member
resulting from the  development or  commercialization  activities of the Grantee
Member  relating  to Company  Inventions).  Such  non-exclusive  licenses  shall
contain  such other  commercially  reasonable,  fair  market  value terms as the
parties shall in good faith agree.


                                       26


                                  ARTICLE VIII
                  BOOKS, RECORDS, ACCOUNTING AND TAX ELECTIONS

     8.1. Bank  Accounts.  All funds of the Company shall be deposited in a bank
account or accounts opened in the Company's name. The Management Committee shall
determine the  institution or  institutions at which the accounts will be opened
and  maintained,  the types of accounts and the persons who will have  authority
with respect to the accounts and the funds therein.

     8.2.  Fiscal Year.  Pursuant to Section 3.4 hereof,  the Fiscal Year of the
Company for both  accounting and tax purposes shall be the calendar year.

     8.3. Method of Accounting.  The Company's  books (for accounting  purposes)
shall be maintained in accordance with generally accepted accounting principles.
The  determinations of the Management  Committee or the Tax Matters Partner,  as
the case may be, with respect to the treatment of any item or its allocation for
federal, state or local income tax purposes shall be binding upon all Members so
long as that  determination  is not inconsistent  with any express  provision of
this Agreement, provided that any determinations made by the Tax Matters Partner
are subject to the approval of CYTOGEN.

     8.4.  Books and  Records.  The books and  records of the  Company  shall be
maintained at the  Company's  expense under the  supervision  of the  Management
Committee at such office as the Management  Committee shall approve,  and may be
examined and copied there by any Member or its duly  authorized  representatives
at reasonable  times and upon  reasonable  notice.  The Company shall furnish to
each Member,  no later than 30 calendar  days after the end of each of the first
three fiscal  quarters,  quarterly and  year-to-date  statements of income and a
balance sheet as of the end of that  quarter.  The Company shall furnish to each
Member,  no later  than 45  calendar  days  after the end of each  Fiscal  Year,
financial  statements  of the Company with respect to that year  prepared by the
Company's  accountant  and  audited  by  the  accounting  firm  selected  by the
Management  Committee.  The  Company  will seek to  engage  the  services  of an
independent  auditing firm as its independent auditor upon terms satisfactory to
the Company.  The  financial  statements  shall  include a balance  sheet of the
Company as of the end of the Fiscal Year, a statement of operations, a statement
of Members' Interests and a statement of changes in cash flow of the Company for
the year. The Company shall also furnish to each Member copies of any additional
financial  reports  delivered  by the  Company to its  lenders and copies of all
financial reports.

     8.5.  Tax  Information.  Not later than the date of  delivery of the annual
financial  statements  pursuant to Section 8.4 hereof, the Management  Committee
shall cause the Company's  accountants to furnish to each Member any information
required by that Member to complete any income tax return that it is required to
file with respect to the year to which such  financial  statements  relate.  The
Company shall also furnish tax information to the Members on an interim basis to
the extent the Management Committee determines appropriate.


                                       27


                                   ARTICLE IX
                                MARKETING RIGHTS

     9.1. Grant of North  American  Marketing  Rights.  Subject to the terms and
conditions  described  herein,  the  LLC  hereby  grants  to  CYTOGEN  exclusive
marketing rights with respect to Licensed Products sold in the United States and
Canada (the "North American Territory").  The exercise of such rights by CYTOGEN
is  conditioned  on CYTOGEN's  capability to perform the  marketing,  detailing,
distribution  and  other  promotional  and  selling   activities   (hereinafter,
"marketing  activities")  required  to be  performed  hereunder  and  under  the
Marketing Agreement (as hereinafter defined). Such determination shall take into
consideration  CYTOGEN's  ability to perform the  necessary  sales and marketing
functions  based  upon  an  assessment  of its  existing  sales,  marketing  and
distribution capabilities compared to those of other companies promoting similar
products to similar  market  segments,  as well as such other  factors as may be
reasonably relevant.

     9.2.  Diligence  Obligations.  CYTOGEN shall use diligent efforts to market
Licensed  Products in the North American  Territory  ("Diligent  Efforts").  For
purposes of the  foregoing,  "Diligent  Efforts"  shall mean  carrying  out such
obligation  in a  sustained  manner  consistent  with the  efforts a party would
devote to a product of similar market  potential,  profit potential or strategic
value resulting from its own research  efforts to which such party has exclusive
rights based on conditions  then  prevailing.  Diligent  Efforts  requires:  (i)
developing a strategic plan for product launch and subsequent market penetration
with defined  objectives;  (ii)  establishing  systems and protocols  reasonably
designed to achieve such objectives;  (iii) allocating  appropriate resources to
support such systems and protocol;  (iv) promptly  assigning  responsibility for
executing  all phases of the Marketing  Plan to specific  employees who are held
accountable for discharging their assigned responsibilities;  and (v) monitoring
on an ongoing  basis the  execution  of the  Marketing  Plan and its success and
making such changes as are  warranted by market and/or  operational  conditions.
CYTOGEN shall provide the LLC with access to all relevant records and personnel,
during normal business hours and with reasonable advance notice, under customary
confidentiality  conditions,  for the purpose of determining  the utilization by
CYTOGEN of Diligent Efforts to commercialize Licensed Products.

     9.3. Assistance by Progenics; Contingent Grant of Rights.(a) Subject to the
terms and conditions  described  herein,  Progenics  shall be entitled to assist
CYTOGEN, under the direction of CYTOGEN, in connection with marketing activities
regarding  Licensed  Products in any  territory  (including  the North  American
Territory)  in  which  CYTOGEN  has  been  granted  or is  subsequently  granted
marketing  rights  pursuant  hereto.  The  assistance  by Progenics in marketing
activities  shall be  conditioned  upon  Progenics'  capability  to augment in a
commercially  significant  manner the  marketing  activities  of CYTOGEN (or any
other person then responsible for marketing  Licensed  Products).  The nature of
the assistance in marketing  activities provided by Progenics will be determined
in good faith by Progenics and CYTOGEN,  with the approval of the LLC, from time
to time based on Progenics' capabilities.

                                       28



     (b) [CONFIDENTIAL TREATMENT HAS BEEN REQUESTED]

     9.4. Marketing Agreement. The LLC, CYTOGEN and Progenics shall negotiate in
good  faith  the  terms  of  a  Product  Marketing   Agreement  (the  "Marketing
Agreement") to be entered into after the completion of Phase II clinical  trials
with respect to any Licensed Product.  The Marketing Agreement shall be based on
the terms set forth in this  Article IX, shall  include,  but not be limited to,
provisions  relating to marketing,  sales,  pricing and distribution of Licensed
Product and shall further define the rights, responsibilities and obligations of
the LLC,  CYTOGEN and Progenics with respect  thereto.  No term of the Marketing
Agreement shall be in conflict with any material term of this Article IX without
the written  agreement of the parties  hereto.  Until the terms of the Marketing
Agreement are agreed upon, such parties acknowledge and agree that the terms set
forth in this  Article  IX are fully  binding  and  enforceable.  The  Marketing
Agreement  shall  include  the  following  terms in  addition to the other terms
described above:

     (a) At least one year in advance of the anticipated  commercial  launch (as
determined in good faith by the LLC) of each Licensed Product in each country in
the North American  Territory,  CYTOGEN shall submit a plan (a "Marketing Plan")
for approval by the LLC for such commercial  launch and the subsequent period of
twelve months plus any subsequent  period prior to the start of a calendar year.
For each calendar year  thereafter,  CYTOGEN shall submit a Marketing  Plan with
respect to, and at least one year prior to, such  calendar  year  describing  in
reasonable  detail the marketing  activities for each such Licensed  Product for
approval  by the LLC.  The LLC's  approval  of any  Marketing  Plan shall not be
unreasonably  withheld.  Each  Marketing  Plan shall include an overall level of
anticipated product detailing,  promotion, marketing and sales efforts regarding
the period covered  thereby,  a resource  commitment on the part of CYTOGEN with
respect  thereto,  market and sales  forecasts and pricing  analysis,  a monthly
budget and,  with respect to  commercial  launch,  an  estimated  launch date of
product  marketing  and promotion  activities.  Each  Marketing  Plan shall also
include the general operating  guidelines and strategies for targeting,  pricing
and discounting Licensed Products to customers,  a detailed budget for marketing
and distribution  activities and a forecast product line contribution  statement
for the applicable calendar year.

     (b)  The LLC  may  from  time to time  review  with  CYTOGEN  such  matters
regarding marketing activities as it reasonably requests. CYTOGEN, Progenics and
the  LLC  agree  to  facilitate  communication  and  cooperation  between  their
respective   organizations  in  order  to  maximize  the  success  of  marketing
activities.

     (c) CYTOGEN shall  develop all written  sales,  promotion  and  advertising
materials  relating to the  commercialization  of Licensed Products in the North
American  Territory.  The general  form and content of such  materials  shall be
subject to annual approval of the LLC and general and specific implementation by
CYTOGEN. Ownership of all names, tradenames, trademarks, service marks and other
designations of Licensed Products (including any related registrations) shall be

                                       29


vested in the LLC. In any given  country,  any given  Licensed  Product shall be
marketed under only one tradename, except as agreed to by the LLC.

     (d) The LLC shall be responsible for the cost of all advertising, sales and
promotion   materials,   market  research  and  Phase  IV  studies   ("Marketing
Materials")  reasonably  incurred  in  connection  with  a  previously  approved
Marketing Plan. The LLC will at all times own the Marketing Materials.

     (e) The LLC will have  responsibility  for manufacturing  finished packaged
product,  both for sale and for  promotional  samples.  The LLC will  also  have
responsibility for manufacturing clinical supplies for any Phase IV studies. The
LLC will  purchase  and pay for all raw  (active  and  inactive)  materials  and
packaging materials (collectively, "Manufacturing Materials") from third parties
necessary to  manufacture  product.  The LLC will at all times have title to the
Manufacturing  Materials,  work-in-process  product and final  packaged  product
(collectively,  "Inventory")  until sale. The LLC shall have  responsibility for
ensuring that  sufficient  Inventory is available to satisfy sales  requirements
pursuant to customer  orders and for procuring and paying for space to warehouse
Inventory.  The LLC shall  have  custodial  and  managerial  responsibility  for
Inventory.

     (f)  CYTOGEN  shall be  responsible  for  procuring  order  processing  and
distribution services for product. CYTOGEN shall have managerial  responsibility
for order processing, including processing customer orders and billing customers
for shipments in  satisfaction  of their orders,  and for product  distribution,
including shipping product in satisfaction of customer orders.

     (g) The LLC shall be entitled to inspect and audit CYTOGEN's and Progenics'
books and  records  pertaining  to  marketing  activities  relating  to Licensed
Products for legitimate  business  purposes under such terms as may be set forth
in the Marketing Agreement.

     9.5.  Negotiation  Rights.  (a) In the  event  that the LLC  determines  to
license, engage, or otherwise contract with or authorize a person other than the
LLC to engage in marketing  activities with respect to a Licensed Product in any
territory  other than in the North American  Territory,  the LLC shall so notify
CYTOGEN  and  negotiate  in good faith with  CYTOGEN  the terms of an  agreement
regarding marketing activities with respect to any such Licensed Product in such
territory. As a condition to any such negotiations, CYTOGEN shall demonstrate to
the LLC's reasonable  satisfaction CYTOGEN's capability to perform the marketing
activities desired by the LLC in the relevant territory. If CYTOGEN is unable to
satisfy  such  condition,  or if  CYTOGEN  does not  desire  to, or is unable to
negotiate any such agreement, or any such agreement is subsequently  terminated,
the LLC shall so notify  Progenics and negotiate in good faith with  Progenics a
marketing agreement as described above. As a condition to any such negotiations,
Progenics  shall  demonstrate to the LLC's  reasonable  satisfaction  Progenics'
capability  to  perform  the  marketing  activities  desired  by the  LLC in the
relevant  territory.  Any such  determination as to the capability of CYTOGEN or
Progenics shall take into  consideration the relevant party's ability to perform

                                       30



the  necessary  sales and marketing  functions  based upon an assessment of such
party's  existing sales,  marketing and  distribution  capabilities  compared to
those of other companies  promoting similar products to similar market segments,
as well as such other factors as may be reasonably relevant.

     (b) If CYTOGEN  elects not to  exercise  the  marketing  rights it has been
granted under Section 9.1 hereof, or such rights are terminated pursuant to this
Agreement or the Marketing  Agreement,  then the LLC shall so notify  Progenics,
and Progenics  shall be entitled to assume,  on a prospective  basis,  CYTOGEN's
marketing rights hereunder and under the Marketing Agreement.  As a condition to
any such assumption,  Progenics must demonstrate to the reasonable  satisfaction
of the LLC Progenics' capability to perform the marketing activities required to
be performed  hereunder and under the Marketing  Agreement.  Such  determination
shall take into consideration Progenics' ability to perform the necessary sales,
marketing and  distribution  functions  based upon an assessment of its existing
sales and marketing  capabilities compared to those of other companies promoting
similar  products to similar market  segments,  as well as such other factors as
may be reasonably relevant.  If Progenics assumes such rights, such rights shall
be terminable  under the same  circumstances as such rights were terminable when
held by CYTOGEN.

     9.6.  Marketing  Compensation.  CYTOGEN and Progenics  shall be entitled to
compensation  for  marketing  activities  conducted  pursuant  hereto  or to the
Marketing Agreement [CONFIDENTIAL TREATMENT HAS BEEN REQUESTED]. For purposes of
this Section 9.6,  [CONFIDENTIAL  TREATMENT HAS BEEN  REQUESTED] as the case may
be, as more specifically described in the Marketing Agreement.

     9.7. Non-Transferability of Rights. The product marketing rights granted by
the LLC pursuant to this  Agreement  shall not be  transferable,  licensable  or
otherwise exercisable by any person or entity other than the party to which such
rights have been granted hereby.

     9.8.  Termination of Rights. The rights granted by the LLC to Progenics and
CYTOGEN  in  Section  9.1 and 9.3 hereof  shall be  subject  to  termination  as
follows:

               9.8.1.  Ownership  Change. In the event that either Progenics' or
          CYTOGEN's  Interest  shall  at any  time  be less  than  [CONFIDENTIAL
          TREATMENT HAS BEEN REQUESTED] of all  then-outstanding  Interests (any
          such party  being  referred  to herein as the  "Diluted  Party"),  the
          rights  granted to the  Diluted  Party  pursuant to Section 9.1 or 9.3
          hereof, as the case may be, shall immediately terminate.  In the event
          that the LLC  determines to issue  additional  ownership  interests to
          third-party  investors,  which  issuance  would result in  substantial
          dilution of Progenics's and CYTOGEN's ownership Interests, the parties
          hereto agree to negotiate in good faith the provisions of this Section
          9.8.1 as it  relates  to any  party  that  has not,  prior to any such
          additional issuance of ownership interests, become a Diluted Party.

                                       31



               9.8.2.  Breach.  In the event that  either  Progenics  or CYTOGEN
          shall breach any of the material  representations or warranties or any
          material terms,  conditions or agreements  contained herein made or to
          be  kept,  observed  and  performed  by it,  then  each of the LLC and
          Progenics  (in the event of a breach by  CYTOGEN)  or CYTOGEN  (in the
          event of a  breach  by  Progenics),  at its sole  option  and  without
          prejudice to any of its other legal or equitable  rights and remedies,
          may, by giving the other  parties  hereto 60 days'  notice in writing,
          identifying with reasonable specificity the breach, and unless (in the
          case of a breach of any term,  condition  or  agreement)  the notified
          party within such 60-day period shall have cured the breach, terminate
          the  rights  granted  to  Progenics  or  CYTOGEN,  as the case may be,
          pursuant to Sections 9.1.

               9.8.3.  Diligence.  The LLC may terminate  the rights  granted to
          CYTOGEN pursuant to Section 9.1 hereof as to any Licensed Product (but
          only as to such Licensed Product) if CYTOGEN  [CONFIDENTIAL  TREATMENT
          HAS BEEN REQUESTED]

     9.9. Retention of Rights. The parties hereto acknowledge and agree that all
marketing  rights not  expressly  granted  by the LLC to  CYTOGEN  or  Progenics
pursuant to this Article IX,  including  without  limitation  product  marketing
rights outside of the North American Territory, are retained by the LLC. The LLC
shall be entitled to retain or dispose of (by license,  sublicense or otherwise)
any such rights in its sole  discretion,  and the proceeds,  if any, of any such
disposition shall inure solely to the LLC.

                                   ARTICLE X
                               DISPUTE RESOLUTION

     10.1. Escalation Procedure. Except as provided in Section 3.6(b) hereof and
except  for any  Deadlock  of the  Management  Committee  which is not  resolved
pursuant to Section  4.1(f) hereof  (including  related  buy/sell  provisions in
Section  4.1(g)  hereof),  all disputes,  controversies,  claims or  differences
between Progenics and CYTOGEN (any such event, a "Dispute")  arising out of this
Agreement,  its interpretation or performance by the Members of their respective
obligations hereunder, including any questions regarding the existence, validity
or termination  hereof,  shall be resolved as described below. The Dispute shall
first be  submitted  (the  "First  Notice of  Dispute")  to the Chief  Executive
Officer of each of the Members for review and  discussion.  Such  persons  shall
meet as soon as possible,  and in any event  within ten calendar  days after the
giving of the First Notice of Dispute, and endeavor in good faith to resolve the
matter.  If these officers do not reach agreement within ten calendar days after
they  meet,  or within 20  calendar  days  after the First  Notice of Dispute is
given,  or  otherwise  agree on another  method of resolving  the  dispute,  the
Dispute shall be resolved pursuant to Section 10.2 hereof.

     10.2.  Arbitration.  (a)  Either  Member  may  make a  demand  for  binding
arbitration  with  respect to any dispute  arising  hereunder by filing with the
other a demand in writing signed by an officer of the Member making such demand.

                                       32


     (b) The Members may agree on one  arbitrator,  but in the event they cannot
agree,  there shall be three, one named in writing by each of the Members within
ten Business Days after demand for  arbitration is given,  and a third chosen by
the two appointed within ten Business Days after their  appointment.  If the two
arbitrators  appointed by the Members do not appoint a third  arbitrator  within
such period, the American Arbitration  Association ("AAA") in New York, New York
shall be retained to appoint a third  arbitrator  within ten Business Days after
the end of such period.  Should  either  Member refuse or neglect to join in the
appointment of the arbitrator(s) or to furnish the arbitrator(s) with any papers
or information demanded, the arbitrator(s) are empowered to proceed ex parte.

     (c)  Arbitration  shall  take  place in New York,  New York (or such  other
location as may be agreed  between  Progenics  and CYTOGEN) at a single  hearing
before the arbitrator(s) of the matter. The arbitrator(s) shall select such time
and place promptly after his/her (or their) appointment,  provided that the time
scheduled  for the hearing  shall not be later than 20  Business  Days after the
appointment  of the last  arbitrator(s).  The  arbitrator(s)  shall give written
notice  thereof to each Member at least ten  Business  Days prior to the date so
fixed. In the event a panel of three arbitrators is necessitated by the Members'
inability to agree upon a single  arbitrator,  such notice of the time and place
of the  hearing  shall  also  identify  the third  member of the  panel.  At the
hearing,  any relevant evidence may be offered by either Member,  and the formal
rules of evidence applicable to judicial proceedings shall not govern.  Evidence
may be  admitted  or  excluded  in the  discretion  of the  arbitrator(s).  Said
arbitrator(s)  shall hear and determine the matter and such determination may be
based on such factors and  consideration  as the  arbitrator(s)  deems  relevant
and/or appropriate. The arbitrator(s)' authority shall be limited to determining
the issue or question  presented  in each  instance  and shall not extend to any
other  aspect of this  Agreement  or the  parties'  relationship  generally.  In
addition,  the  arbitrator(s)  shall not require the LLC to pursue a  particular
research and development  program unless the general  elements thereof have been
approved  by the  Management  Committee.  The  arbitrator(s)  shall  execute and
acknowledge  a binding  decision  in writing  setting  forth the basis for their
decision in  reasonable  detail and cause a copy thereof to be delivered to each
of the Members within ten Business Days of the hearing date.

     (d) The  determination  of the panel  shall be by  majority  vote with each
arbitrator having a single vote. The decision rendered by the arbitrator (or the
majority,  if more than one) shall be final, and judgment may be entered upon it
in accordance with the applicable law in any court of competent jurisdiction.

     (e)  Prior to the  scheduled  hearing  date,  the  Members  shall  agree on
procedures  to be used in  connection  with the  arbitration.  To the extent the
Members  cannot agree upon  procedures,  the  arbitration  shall be conducted in
accordance with the Commercial  Arbitration  Rules of the AAA under the auspices
of the AAA.

     (f) The costs of such arbitration shall be borne by the Company;  provided,
however,  that if the arbitrator(s)  determines that one of the Members acted in
bad faith in submitting the dispute to  arbitration,  such Member shall bear all
costs and expenses  (including  the costs and  expenses of the other  Member) in
connection with the arbitration proceeding.

                                       33

     10.3. Injunctive Relief.  Notwithstanding  anything herein to the contrary,
any Member may seek  interim or  provisional  relief in the form of a  temporary
restraining  order,  preliminary  injunction or other interim  equitable  relief
concerning any Dispute in a court of competent jurisdiction;  provided, however,
that, once the selection of the  arbitrator(s)  is complete,  the  continuation,
termination,  amendment or  modification  of the interim or  provisional  relief
shall be determined by the  arbitrator(s)  and, after an arbitration  hearing is
commenced,  the action, suit or proceeding  commenced in such court seeking such
interim or  provisional  relief  shall be dismissed  by the  stipulation  of all
Members. In the event that the Members fail to stipulate to the dismissal of the
action,  the  Members  agree that the  arbitrator(s)  may  submit a  stipulation
dismissing the action.  The  arbitrator(s) may conduct any hearings or order any
discovery  they deem  necessary  to properly  review the interim or  provisional
relief. This Section 10.3 shall be specifically enforceable by each Member.

                                   ARTICLE XI
                            MISCELLANEOUS PROVISIONS

     11.1.  Assurances.  Each Member shall  execute all  certificates  and other
documents and shall do all such filing, recording,  publishing and other acts as
the Management  Committee deems  appropriate to comply with the  requirements of
law for the  formation and operation of the Company and to comply with any laws,
rules and regulations  relating to the acquisition,  operation or holding of the
property of the Company.

     11.2. Disclaimer of Agency. This Agreement does not create any relationship
beyond the scope set forth herein,  and except as otherwise  expressly  provided
herein, this Agreement shall not constitute any Member the legal  representative
or agent of the  other,  nor shall any  Member  have the right or  authority  to
assume,  create  or incur any  liability  or  obligation,  express  or  implied,
against, in the name of or on behalf of any other Member of the Company.

     11.3.  Entire  Agreement;  Amendment.  This  Agreement  contains a complete
statement  of the  arrangements  among the Members  with  respect to the Company
supersedes all prior  agreements and  understandings  among them with respect to
the Company and may not be amended except by unanimous  written agreement of the
Members.

     11.4. Notices. Any notice or other communication under this Agreement shall
be in writing and shall be considered  given when delivered in person or sent by
facsimile  and  acknowledged  by a  responsible  person  at  the  office  of the
recipient,  one day after being sent by a major overnight courier,  or four days
after being mailed by registered mail, return receipt requested,  to the Members
at the addresses set forth below their names on the Schedule A hereto.

                                       34


     11.5.  Counterparts.  The Members may execute this Agreement in two or more
counterparts,  which shall, in the aggregate, be signed by all the Members. Each
counterpart shall be deemed an original instrument as against any Member who has
signed it.

     11.6.  Governing Law. This Agreement  shall be governed by and construed in
accordance  with the law of the State of Delaware  applicable to agreements made
and to be performed in Delaware.

     11.7. Binding Effect. This Agreement shall be binding on all successors and
assigns of the  Members  and inure to the  benefit of the  respective  permitted
successors  and  assigns of the  Members,  except to the  extent of any  express
contrary provision in this Agreement.

     11.8.  Severability.  If any  provision  of this  Agreement  is  invalid or
unenforceable, the balance of this Agreement shall remain in effect and shall be
enforceable  to the maximum  extent  permitted by law,  and if any  provision is
inapplicable  to any  person  or  circumstance,  it  shall  nevertheless  remain
applicable to all other persons and circumstances.

     11.9.  Survival  of Rights,  Duties and  Obligations.  Termination  of this
Agreement for any cause shall not release either Member from any liability which
at the time of  termination  has already  accrued to the other Member  hereto or
which  thereafter  may accrue in respect  of any act or  omission  prior to such
termination,  nor  shall  any  such  termination  hereof  affect  in any way the
survival of and right,  duty or  obligation  of either Member which is expressly
stated elsewhere in this Agreement to survive termination hereof.

     11.10.  Captions and  Exhibits.  Titles or captions of Sections or Articles
contained in this Agreement are inserted only as a matter of convenience and for
reference  and in no way define,  limit,  extend or  describe  the scope of this
Agreement or the intent of any  provision  hereof.  All  Exhibits and  Schedules
attached  hereto  shall be  considered  a part hereof as though  fully set forth
herein.

     11.11. Specific Performance.  The Members acknowledge that monetary damages
may not be an adequate  remedy for  violations  of this  Agreement  and that any
Member may, in its sole  discretion,  through  arbitration  or  otherwise  under
Article X or, in  circumstances  where Article X hereof is not applicable,  in a
court of competent jurisdiction, apply for specific performance or injunctive or
other  relief as such  arbitrator  or court may deem just and proper in order to
enforce  this  Agreement  or to  prevent  violation  hereof  and,  to the extent
permitted by applicable  law, each Member waives any objection to the imposition
of such relief.

     11.12.  Assignability.  Except as otherwise provided in Section 6.1 hereof,
neither  this  Agreement  nor any  Interest,  including  the  right  to  receive
distributions,  shall be assignable by either Member without the written consent
of the other,  and any attempted  assignment  without such consent shall be null
and void.  This  Agreement  shall be binding upon the  successors  and permitted

                                       35


assigns of the Members.  Any such successor or permitted assign shall be subject
to the same rights and  obligations  as the original  Member  hereunder.

     11.13.  Confidentiality.  (a) As used in this Section 11.13,  "Confidential
Information"  means all confidential  and proprietary  business,  technical,  or
financial information relating to the matters discussed herein.

     (b) In order to protect the  Confidential  Information of any Member hereto
(in such capacity,  the  "Disclosing  Member") that has become  available to any
other Member hereto (in such  capacity,  the  "Receiving  Member"),  each Member
agrees as follows:

     (i)  Each  Member  agrees  that  it will  make  no use of any  Confidential
Information  except  in  furtherance  of  the  purposes   contemplated  by  this
Agreement.

     (ii) Each Member agrees that it will not, without the prior written consent
of the other Member, disclose to any third party Confidential Information (which
for purposes of this Section  11.13(b)  shall  include the terms or existence of
this Agreement or of the PSMA/PSMP License  Agreement or the Services  Agreement
or other matters relating to the collaboration  contemplated hereby and thereby)
received in its capacity as Receiving  Member so long as such Member is a member
of the Company and for a period of five years thereafter.

     (iii) Notwithstanding the foregoing:

          (1)  Each Member may disclose Confidential Information to those of its
               representatives,  employees  and agents  ("Representatives")  who
               have a need to know such Confidential  Information in relation to
               the matters  discussed  herein and who are under  obligations  of
               confidentiality  and  non-use  consistent  with  those  set forth
               herein. Any unauthorized  disclosure of Confidential  Information
               by a Member's Representatives shall be a breach by such Member of
               this Section 11.13.

          (2)  Disclosure of Confidential Information is permitted to the extent
               that such  disclosure is required  pursuant to  applicable  laws,
               rules or  regulations  or government  requirement or court order,
               provided however, that the Receiving Member shall promptly notify
               the  Disclosing  Member in writing of the existence or imposition
               of  any  such   requirement  or  order  and  cooperate  with  the
               Disclosing  Member in seeking an appropriate  protective order or
               other  reliable  assurance  that  confidential  treatment will be
               accorded the Confidential Information.

                                       36


     (c) The provisions governing  confidentiality and non-use contained in this
Section 11.13 shall not apply to any Confidential Information which:

               (i)  the  Receiving   Member  can  establish  was  known  to  the
                    Receiving  Member prior to disclosure under or in connection
                    with this Agreement by the Disclosing Member;

               (ii) was in the public domain or the subject of public  knowledge
                    at the time of disclosure  under or in connection  with this
                    Agreement;

               (iii)becomes  part of the public  domain or the subject of public
                    knowledge  through  no  breach by or act of  default  of the
                    Receiving Member;

               (iv) is obtained by the Receiving Member from a third party other
                    than in  breach  of a legal  or  contractual  obligation  of
                    confidentiality  owed by such third party to the  Disclosing
                    Member in  respect  thereof,  the  existence  of which  such
                    obligation  was  known  or  should  have  been  known by the
                    Receiving Member; or

               (v)  the  Receiving   Member  can  establish  was   independently
                    developed   by  it   without   reference   to   Confidential
                    Information received.

     (d)  Termination  of  this  Agreement  shall  not  affect  the  obligations
concerning confidentiality and non-use as set forth in this Section 11.13.


                                       37



                  IN WITNESS  WHEREOF,  the  parties  hereto  have  signed  this
Agreement as of the date first above written.

                         PROGENICS PHARMACEUTICALS, INC.


                         By: /s/  Ronald Prentki
                            Name: Ronald Prentki
                            Title President


                         CYTOGEN CORPORATION


                         By:  /s/ Donald F. Crane, Jr.
                            Name: Donald F. Crane, Jr.
                            Title Vice President General Counsel and
                                  Corporate Secretary


                         PSMA DEVELOPMENT COMPANY LLC


                         By:  /s/ Ronald Prentki
                            Managing Representative


                         By:  /s/  Donald F. Crane, Jr.
                            Managing Representative


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