1
                                                                     EXHIBIT 3.1


                            CERTIFICATE OF AMENDMENT

                                       OF

                          CERTIFICATE OF INCORPORATION

                                       OF

                             ONCOGENE SCIENCE, INC.


            I, the President of Oncogene Science, Inc., a corporation organized
and existing under the laws of the State of Delaware (the "Corporation"), do
hereby certify that (i) Article Fourth of the Corporation's Certificate of
Incorporation has been amended in its entirety to read as set forth below, and
(ii) such amendment was duly adopted in accordance with the provisions of
Section 242 of the General Corporation Law of the State of Delaware.

            FOURTH.  The total number of shares of stock that the Corporation
            shall have authority to issue is 50,000,000 shares of common stock,
            having a par value of $.01 per share, all of the same class.

            IN WITNESS WHEREOF, I have hereunto set my hand and seal as of the
31st day of March, 1993.


(Corporate Seal)

Attest:


/s/ Theresa R. Dragone                          /s/ Gary E. Frashier   (SEAL)
- -----------------------------                   -----------------------
Theresa R. Dragone                              Gary E. Frashier, President
Secretary
   2
                            CERTIFICATE OF AMENDMENT

                                       OF

                          CERTIFICATE OF INCORPORATION

                                       OF

                             ONCOGENE SCIENCE, INC.

                   -----------------------------------------
                   Adopted in accordance with the provisions
                   of Section 242 of the General Corporation
                          Law of the State of Delaware
                   -----------------------------------------

            We, the President and Secretary of ONCOGENE SCIENCE, INC., a
corporation existing under the laws of the State of Delaware, do hereby certify
as follows:

            FIRST:  That Article IX of the Certificate of Incorporation of said
corporation has been amended in its entirety to read as follows:

                                   ARTICLE IX

                         INDEMNIFICATION AND INSURANCE

                  SECTION 1.  Right to Indemnification.  Each person who was or
            is made a party or is threatened to be made a party to or is
            involved in any threatened, pending or completed action, suit or
            proceeding, whether civil, criminal, administrative or
            investigative ("Proceeding"), by reason of the fact that he, or a
            person of whom he is the legal representative, is or was the
            director, officer, employee or agent of the Corporation or is or
            was serving at the request of the Corporation as a director,
            officer, employee or agent of another corporation or of a
            partnership, joint venture, trust or other enterprise, including
            service with respect to employee benefit plans, whether the basis
            of such Proceeding is alleged action in an official capacity as a
            director, officer, employee or agent or in any other capacity while
            serving as a director, officer, employee or agent, shall be
            indemnified and held harmless by the Corporation to the fullest
            extent authorized by the Delaware General Corporation Law, as the
            same exists or may hereafter be amended (out, in the case of





                                      -1-
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            any such amendment, only to the extent that such amendment permits
            the Corporation to provide broader indemnification rights than said
            law permitted the Corporation to provide prior to such amendment),
            against all expenses, liability and loss (including attorneys'
            fees, judgments, fines, ERISA excise taxes or penalties and amounts
            paid or to be paid in settlement) reasonably incurred or suffered
            by such person in connection therewith; provided, however, that the
            Corporation shall indemnify any such person seeking indemnity in
            connection with a Proceeding (or part thereof) initiated by such
            person only if the proceeding (or part thereof) was authorized by
            the Board of Directors of the Corporation.  The right to
            indemnification conferred in this Section 1 shall be a contract
            right and shall include the right to be paid by the Corporation
            expenses incurred in defending any such Proceeding in advance of
            its final disposition; provided, however, that if the Delaware
            General Corporation Law requires, the payment of such expenses
            incurred by a director or officer in his capacity as a director or
            officer (and not in any other capacity in which service was or is
            rendered by such person while a director or officer, including,
            without limitation, service to an employee benefit plan) in advance
            of the final disposition of such Proceeding, shall be made only
            upon delivery to the Corporation of an undertaking, by or on behalf
            of such director or officer, to repay all amounts so advanced if it
            should be determined ultimately that such director of officer is
            not entitled to be indemnified under this Section or otherwise.

                  SECTION 2.  Non-Exclusivity of Rights.  The rights conferred
            on any person by Section 1 shall not be exclusive of any other
            right which such person may have or hereafter acquire under any
            statute, provision of the Certificate of Incorporation, by-laws,
            agreement, vote of stockholders or disinterested directors, or
            otherwise.

                  SECTION 3.  Limitation of Liability of Directors.  A director
            of the Corporation shall not be personally liable to the
            Corporation or its stockholders for monetary damages for breach of
            fiduciary duty as a director except for liability (i) for any
            breach of the director's duty of loyalty to the Corporation or its
            stockholders, (ii) for acts or omissions not in good faith or which
            involve intentional misconduct or a knowing violation of law, (iii)
            under Section 174 of the Delaware General





                                      -2-
   4
            Corporation Law, or (iv) for any transaction from which the
            director derived an improper personal benefit.

                  SECTION 4.  Insurance.  The Corporation may maintain
            insurance, at its expense, to protect itself and any such director,
            officer, employee or agent of the Corporation or another
            corporation, partnership, joint venture, trust or other enterprise
            against any such expense, liability or loss, whether or not the
            Corporation would have the power to indemnify such person against
            such expense, liability or loss under the Delaware General
            Corporation Law.

            SECOND:  That such amendment has been duly adopted in accordance
with the provisions of the General Corporation Law of the State of Delaware by
the affirmative vote of the holders of not less than a majority of the
outstanding stock entitled to vote thereon.

            IN WITNESS WHEREOF, we have signed this certificate this 9th day of
April, 1987.

                                                /s/ Robert E. Ivy
                                                ----------------------------
                                                Robert E. Ivy, President


                                    ATTEST:     /s/ Gary Takata
                                                ----------------------------
                                                Gary Takata, Secretary





                                      -3-
   5
                            CERTIFICATE OF AMENDMENT

                                       OF

                          CERTIFICATE OF INCORPORATION

                                       OF

                             ONCOGENE SCIENCE, INC.

                   -----------------------------------------
                   Adopted in accordance with the provisions
                   of Section 242 of the General Corporation
                          Law of the State of Delaware
                   -----------------------------------------

            We, the President and Secretary of ONCOGENE SCIENCE, INC., a
corporation existing under the laws of the State of Delaware, do hereby certify
as follows:

            FIRST:  That Article FOURTH of the Certificate of Incorporation of
said corporation has been amended in its entirety to read as follows:

                  "FOURTH.  The total number of shares of stock which the
            Corporation shall have authority to issue is 20,000,000 shares of
            common stock, of the par value of $.01 per share, all of the same
            class."

            SECOND:  That such amendment has been duly adopted in accordance
with the provisions of the General Corporation Law of the State of Delaware by
the written consent of the holders of not less than a majority of the
outstanding stock entitled to vote thereon and that written notice of the
corporation action has been given to those stockholders who have not consented
in writing, all in accordance with the provisions of Section 228 of the General
Corporation Law.
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            IN WITNESS WHEREOF, we have signed this certificate this 18th day
of January, 1986.


                                                /s/ Robert E. Ivy
                                                ----------------------------
                                                Robert E. Ivy, President


                                    ATTEST:     /s/ Gary Takata
                                                ----------------------------
                                                Gary Takata, Secretary





                                      -2-
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                            CERTIFICATE OF AMENDMENT

                                       OF

                          CERTIFICATE OF INCORPORATION

                                       OF

                             ONCOGENE SCIENCE, INC.

                        --------------------------------

                            (a Delaware corporation)

                        --------------------------------
                         Adopted in accordance with the
                        provisions of Section 241 of the
                         General Corporation Law of the
                               State of Delaware
                        --------------------------------

            THE UNDERSIGNED, Steven Gelles, sole incorporator of ONCOGENE
SCIENCE, INC., does hereby certify:

            FIRST:      That the Certificate of Incorporation of ONCOGENE
SCIENCE, INC. (the "Corporation") was filed in the office of the Secretary of
State of Delaware on March 6, 1983 and a certified copy thereof was recorded in
the office of the Recorder of Kent County, Delaware on March 16, 1983.

            SECOND:     That the Corporation has not received payment for its
stock.

            THIRD:      That the Certificate of Incorporation of the
Corporation is amended as follows:

                  (i)   By striking out paragraph FIRST thereof as it now
                        exists and inserting in lieu thereof ARTICLE I, reading
                        as follows:

                                   ARTICLE I

                                      NAME

             The name of the corporation is ONCOGENE SCIENCE, INC.

                  (ii)  By striking out paragraph SECOND thereof as it now
                        exists and inserting in lieu thereof ARTICLE II,
                        reading as follows:
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                                   ARTICLE II

                     REGISTERED OFFICE AND REGISTERED AGENT

            The registered office of the Corporation in the State of Delaware
is located at 229 South State Street, City of Dover, County of Kent.  The name
and the address of the registered agent of the Corporation in the State of
Delaware is The Prentice-Hall Corporation System, Inc., 229 South State Street,
Dover, Delaware.

                  (iii) By striking out paragraph THIRD thereof as it now
                        exists and inserting in lieu thereof ARTICLE III,
                        reading as follows:

                                  ARTICLE III

                         CORPORATE PURPOSES AND POWERS

            The nature of the business of the Corporation, or the objects or
purposes to be transacted, promoted or carried on by the Corporation are any
and all lawful acts or activities for which corporations may be organized under
the General Corporation Law of Delaware, including but not limited to research
and development, manufacture, production, purchase or acquisition, and sale,
licensing, leasing, or disposition of materials, supplies, substances,
chemicals or equipment used or useful in the field of biotechnology or in any
other field in which such materials, supplies, substances, chemicals or
equipment may profitably be used.

                  (iv)  By striking out paragraph FOURTH thereof as it now
                        exists and inserting in lieu thereof ARTICLE IV,
                        reading as follows:

                                   ARTICLE IV

                                 CAPITAL STOCK

            The amount of the total authorized capital stock of this
Corporation is One Hundred Thousand Dollars ($100,000) consisting of Ten
Million (10,000,000) common shares, with a par value of one cent ($.01) each.

                  (v)   By striking out paragraph FIFTH thereof as it now
                        exists and inserting in lieu thereof ARTICLE V, reading
                        as follows:

                                   ARTICLE V

                                  INCORPORATOR

            The name and mailing address of the sole incorporator of the
Corporation is:





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            Name                    Address
            ----                    -------

            Steven Gelles           122 East 42nd Street
                                    Suite 606
                                    New York, New York 10168

                  (vi)  By adding thereto additional ARTICLES VI - XI, reading
                        as follows:

                                   ARTICLE VI

                          POWERS OF BOARD OF DIRECTORS

            In addition to and not in limitation of the powers conferred by
statute, the board of directors of the Corporation expressly is authorized:

                  (a)   To make, adopt, alter, amend or repeal the by-laws,
      except as otherwise expressly provided in any by-law adopted by the
      holders of Capital Stock of the Corporation entitled to vote thereon.
      Any by-law may be altered, amended or repealed by the holders of Capital
      Stock of the Corporation entitled to vote thereon at any annual meeting
      or at any special meeting called for that purpose;

                  (b)   To authorize and cause to be executed mortgages, liens,
      and other security interests upon the real and personal property of the
      Corporation;

                  (c)   To determine the use and disposition of any surplus and
      net profits of the Corporation including, without limitation by
      specification, the determination of the amount of working capital
      required by the Corporation, to set apart out of any of the funds of the
      Corporation, whether or not available for dividends, a reserve or
      reserves for any proper purpose and to abolish any such reserve in the
      manner in which it was created;

                  (d)   To designate, by resolution passed by a majority of the
      members of the board of directors, one or more committees, each
      consisting of two or more directors of the Corporation which, to the
      extent provided in the resolution designating the committee or provided
      in the by-laws of the Corporation, have and may exercise, subject to the
      provisions of the General Corporation Law of Delaware, all the powers and
      authority of the board of directors in the management of the business and
      affairs of the Corporation.  Such committee or committees may authorize
      the seal of the Corporation to be affixed to all papers which may require
      it.  Such committee or committees shall have such name or names as may be
      provided in the by-laws of the Corporation or as may be determined from
      time to time by resolution adopted by the board of directors;





                                      -3-
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                  (e)   To grant rights or options entitling the holders
      thereof to purchase from the Corporation shares of its Capital Stock
      evidenced by or in such instrument or instruments as shall be approved by
      the board of directors.  The terms upon which, the time or times at or
      within which, the persons to whom, and the price or prices at which any
      such rights or options may be issued and any shares of Capital Stock may
      be purchased from the Corporation upon the exercise of any such right or
      option shall be such as shall be fixed in a resolution or resolutions
      adopted by the board of directors providing for the creation and issuance
      of such rights or options.  In the absence of actual fraud in the
      transaction, the judgment of the board of directors as to the
      consideration for the issuance of such rights or options and the
      sufficiency thereof shall be conclusive.  No such rights or options shall
      be invalidated or in any way affected by the fact that any director shall
      be a grantee thereof or shall vote for the issuance of such rights or
      options to himself or for any plan pursuant to which he may receive any
      such rights or options;

                  (f)   To adopt such plans as from time to time may be
      approved by the board of directors for the purchase by officers or
      employees of the Corporation and of any corporation either affiliated
      with or a subsidiary of the Corporation of shares of Capital Stock of the
      Corporation.  The terms upon which, the time or times at or within which
      and the price or prices at which shares of Capital Stock may be purchased
      from the Corporation pursuant to such plan shall be fixed in the plan by
      the board of directors.  No such plan which is not at the time of
      adoption unreasonable or unfair shall be invalid or in any way affected
      because any director shall be entitled to purchase shares of Capital
      Stock of the Corporation thereunder and shall vote for such plan;

                  (g)   To adopt or assume and carry out such plans as from
      time to time may be approved by the board of directors for the
      distribution among the officers or employees of the Corporation and of
      any corporation which is affiliated with or a subsidiary of the
      Corporation, or any of them, in addition to their regular salaries, of
      part of the earnings of the Corporation, in consideration for or in
      recognition of services rendered by such officers or employees or as an
      inducement to future efforts.  No such plan which is not at the time of
      adoption or assumption unreasonable or unfair shall be invalidated or in
      any way affected because any director shall be a beneficiary thereunder
      or shall vote for any plan under which he may benefit or for any
      distribution thereunder in which he may participate;

                  (h)   To adopt such pension, profit sharing, retirement,
      deferred compensation or other employee benefit plans or provisions as
      may, from time to time, be approved by the board of directors, providing
      for pensions, profit sharing, retirement income, deferred compensation or
      other benefits for officers or employees of the Corporation and of any
      corporation which is affiliated with or a subsidiary of the Corporation,
      or any of them, in consideration for or in recognition of the services
      rendered by such officers or employees or as an inducement to future
      efforts.  No





                                      -4-
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      such plan or provision, which is not at the time of adoption unreasonable
      or unfair shall be invalidated or in any way affected because any
      director shall be a beneficiary thereunder or shall vote for any plan or
      provision under which he may benefit; and

                  (i)   To exercise, in addition to the powers and authorities
      herein or by law conferred upon the board of directors, any such powers
      and authorities and do all such acts and things as may be exercised or
      done by the Corporation subject, nevertheless, to the provisions of the
      General Corporation Law of Delaware, this certificate of incorporation
      and any by-laws from time to time adopted by the holders of Capital Stock
      of the Corporation entitled to vote thereon.

                                  ARTICLE VII

              MEETINGS AND CONSENTS OF STOCKHOLDERS AND DIRECTORS;
                   CORPORATION BOOKS; ELECTIONS OF DIRECTORS;
                                  AND NOTICES

            Meetings of holders of Capital Stock of the Corporation and of the
board of directors and of any committee thereof may be held outside the State
of Delaware if the by-laws so provide.  Except as otherwise provided by law or
by this certificate of incorporation, any action required to be taken at any
annual, or special meeting of stockholders of the Corporation or any action
which may be taken at any annual or special meeting of such stockholders may be
taken without a meeting, without prior notice and without a vote, if a consent
in writing, setting forth the action so taken, shall be signed by the holders
of outstanding Capital Stock having not less than the minimum number of votes
that would be necessary to authorize or to take such action at a meeting at
which all shares of Capital Stock entitled to vote thereon were present and
voted.  Prompt notice of the taking of the corporate action without a meeting
by less than unanimous written consent shall be given to those stockholders who
have not consented in writing.  Any action required or permitted to be taken at
any meeting of the board of directors or of any committee thereof may be taken
without a meeting as provided by statute if the by-laws of the Corporation so
provide.  Except as otherwise provided by law, the books of the Corporation may
be kept outside the State of Delaware at such place or places as may be
designated from time to time by the board of directors or in the by-laws of the
Corporation.  The elections of directors need not be by ballot unless the
by-laws of the Corporation so provide.  Any notice permitted or required by
this certificate of incorporation shall be written, signed by the sender and
mailed, postage prepaid, in the United States by certified or registered mail.

                                  ARTICLE VIII

                    TRANSACTIONS WITH DIRECTORS AND OFFICERS

            No contract or transaction between the Corporation and one or more
of its directors or officers or between the Corporation and any other
corporation, partnership,





                                      -5-
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association or other organization, in which one or more of its directors or
officers are directors or officers or have a financial interest, shall be void
or voidable solely for such reason or solely because the director or officer is
present at or participates in the meeting of the board of directors or
committee thereof which authorizes the contract or transaction or solely
because his or their votes are counted for such purpose if: (a) The material
facts as to his relationship or interest and as to the contract or transaction
are disclosed or are known to the board of directors or the committee and the
board of directors or the committee in good faith authorizes the contract or
transaction by the affirmative vote of a majority of the disinterested
directors even though the disinterested directors may be less than a quorum; or
(b) the material facts as to his relationship or interest and as to the
contract or transaction are disclosed or are known to the stockholders entitled
to vote thereon and the contract or transaction is specifically approved in
good faith by vote of the stockholders; or (c) the contract or transaction is
fair as to the Corporation as of the time it is authorized, approved or
ratified by the board of directors, a committee thereof or the stockholders.
Common or interested directors may be counted in determining the presence of a
quorum at a meeting of the stockholders or the board of directors or of a
committee which authorizes the contract or transaction.

                                   ARTICLE IX

                         INDEMNIFICATION AND INSURANCE

            SECTION 1. Indemnification by Corporation.

                  (a)   Any person who was or is a party or is threatened to be
      made a party to any threatened, pending or completed action, suit or
      proceeding, whether civil, criminal, administrative or investigative
      (other than action by or in the right of the Corporation) by reason of
      the fact that he is or was a director, officer, employee or agent of the
      Corporation or is or was serving at the request of the Corporation as a
      director, officer, employee or agent of another corporation, partnership,
      joint venture, trust or other enterprise, shall be indemnified by the
      Corporation, unless similar indemnification is provided by such other
      corporation or organization which may be involved (any funds received by
      any person as a result of the provisions of this Article shall be deemed
      an advance against his receipt of any such other indemnification from any
      such other corporation or organization), against expenses (including
      attorneys' fees), judgments, fines and amounts paid in settlement
      actually and reasonably incurred by such person in connection with such
      action, suit or proceeding if he acted in good faith and in a manner he
      reasonably believed to be in or not opposed to the best interests of the
      Corporation and, with respect to any criminal action or proceeding, had
      no reasonable cause to believe his conduct was unlawful.  Any such person
      who could be indemnified pursuant to the preceding sentence except for
      the fact that the subject action or suit is or was by or in the right of
      the Corporation shall be indemnified by the Corporation against expenses
      (including attorneys' fees) actually and reasonably incurred by him, in
      connection with the defense or settlement of such





                                      -6-
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      action or suit except that no indemnification shall be made in respect of
      any claim, issue or matter as to which such person shall have been
      adjudged to be liable for negligence or misconduct in the performance of
      his duties to the Corporation unless and only to the extent that the
      Court of Chancery of the State of Delaware or the court in which such
      action or suit was brought shall determine upon application that, despite
      the adjudication of liability but in view of all the circumstances of the
      case, such person is fairly and reasonably entitled to indemnity for such
      expenses which the Court of Chancery or such other court shall deem
      proper;

                  (b)   To the extent that a director, officer, employee or
      agent of the Corporation has been successful on the merits or otherwise
      in defense of any action, suit or proceeding referred to in paragraph (a)
      of this Section 1 or in defense of any claim, issue or matter therein, he
      shall be indemnified by the Corporation against expenses (including
      attorneys' fees) actually and reasonably incurred by him in connection
      therewith without the necessity of any action being taken by the
      Corporation other than the determination, in good faith, that such
      defense has been successful.  In all other cases wherein indemnification
      is provided by this Article, unless ordered by a court, indemnification
      shall be made by the Corporation only as authorized in the specific case
      upon a determination that indemnification of the director, officer,
      employee or agent is proper in the circumstances because he has met the
      applicable standard of conduct specified in this Article.  Such
      determination shall be made: (1) By the board of directors by a majority
      vote of a quorum consisting of directors who were not parties to such
      action, suit or proceeding; or (2) if such a quorum is not obtainable or,
      even if obtainable, a quorum of disinterested directors so directs, by
      independent legal counsel in a written opinion; or (3) by the holders of
      a majority of the Capital Stock outstanding;

                  (c)   The termination of any action, suit or proceeding by
      judgment, order, settlement, conviction or upon a plea of nolo contendere
      or its equivalent shall not create, of itself, a presumption that the
      person seeking indemnification did not act in good faith and in a manner
      which he reasonably believed to be in or not opposed to the best
      interests of the Corporation and, with respect to any criminal action or
      proceeding, had reasonable cause to believe that his conduct was
      unlawful.  Entry of a judgment by consent as part of a settlement shall
      not be deemed final adjudication of liability for negligence or
      misconduct in the performance of duty or of any other issue or matter;

                  (d)   Expenses incurred in defending a civil or criminal
      action, suit or proceeding may be paid by the Corporation in advance of
      the final disposition of such action, suit or proceeding as authorized by
      the board of directors in the specific case upon receipt of an
      undertaking by the director, officer, employee or agent involved to repay
      such amount unless it ultimately shall be determined that he is entitled
      to be indemnified by the Corporation; and





                                      -7-
   14
                  (e)   The indemnification provided in this Article shall not
      be deemed exclusive of any other rights to which those seeking
      indemnification may be entitled under any by-law, agreement, vote of
      stockholders or disinterested directors or otherwise, both as to action
      in an official capacity and as to action in another capacity while
      holding such office, and shall continue as to a person who has ceased to
      be a director, officer, employee or agent and shall inure to the benefit
      of the heirs, executors and administrators of such person.

            SECTION 2. Insurance.  By action of the board of directors,
notwithstanding any interest of the directors in the action, the Corporation
may purchase and maintain insurance, in such amounts as the board of directors
deems appropriate, on behalf of any person who is or was a director, officer,
employee or agent of the Corporation or is or was serving at the request of the
Corporation as a director, officer, employee or agent of another corporation,
partnership, joint venture, trust or other enterprise against any liability
asserted against him and incurred by him in any such capacity or arising out of
his status as such, whether or not the Corporation shall have the power to
indemnify him against such liability under the provisions of this Article.

                                   ARTICLE X

                 COMPROMISE OR ARRANGEMENT BETWEEN CORPORATION
                       AND ITS CREDITORS OR STOCKHOLDERS

            Whenever a compromise or arrangement is proposed between this
Corporation and its creditors or any class of them and/or between this
Corporation and its stockholders or any class of them, any court of equitable
jurisdiction within the State of Delaware may, on the application in a summary
way of this Corporation or of any creditor or stockholder thereof or on the
application of any receiver or receivers appointed for this Corporation under
the provisions of Section 291 of Title 8 of the Delaware Code or on the
application of trustees in dissolution or of any receiver or receivers
appointed for this Corporation under the provisions of Section 279 of Title 8
of the Delaware Code order a meeting of the creditors or class of creditors,
and/or of the stockholders or class of stockholders of this Corporation, as the
case may be, to be summoned in such manner as the said court directs.  If a
majority in number representing three-fourths in value of the creditors or
class of creditors, and/or of the stockholders or class of stockholders of this
Corporation, as the case may be, agree to any compromise or arrangement and to
any reorganization of this Corporation as a consequence of such compromise or
arrangement, the said compromise or arrangement and the said reorganization
shall, if sanctioned by the court to which the said application has been made,
be binding on all the creditors or class of creditors, and/or on all the
stockholders or class of stockholders, of this Corporation, as the case may be,
and also on this Corporation.





                                      -8-
   15
                                   ARTICLE XI

                   RESERVATION OF RIGHT TO AMEND CERTIFICATE
                                OF INCORPORATION

            The Corporation reserves the right to amend, alter, change or
repeal any provisions contained in this certificate of incorporation in the
manner now or hereafter prescribed by law and by this certificate of
incorporation.  All the provisions of this certificate of incorporation and all
rights and powers conferred in this certificate of incorporation on
stockholders, directors and officers are subject to such reserved power.

            FOURTH:     That such amendment has been duly adopted in accordance
with the provision of Section 241 of the General Corporation Law of the State
of Delaware.

            IN WITNESS WHEREOF, I have signed this certificate this 15th day of
April, 1983.


                                                /s/ Steven Gelles
                                                --------------------------
                                                STEVEN GELLES





                                      -9-
   16
                                  CERTIFICATE

                                       OF

                                 INCORPORATION

                                       OF

                             ONCOGENE SCIENCE, INC.


FIRST:      The name of this Corporation is ONCOGENE SCIENCE, INC.

SECOND:     Its Registered Office in the State of Delaware is to be located at
            600 Bay Road, in the City of Dover, Zip Code 19901.  The Registered
            Agent in charge thereof is Ms. Pam Goldsborough.

THIRD:      The purpose of the Corporation is to perform research and to
            develop, manufacture, produce, purchase or otherwise acquire, and
            to sell, license, lease or otherwise dispose of materials,
            supplies, substances, chemicals or equipment used or useful in the
            field of Biotechnology or in any other field in which such
            materials, supplies, substances, chemicals or equipment may be
            profitably used and to engage in any lawful act or activity for
            which corporations may be organized under the General Corporation
            Law of Delaware.

FOURTH:     The amount of the total authorized capital stock of this
            Corporation is One Hundred Thousand Dollars ($100,000) divided into
            Ten Million (10,000,000) shares, of One Cent ($.01) each.

FIFTH:      The name and mailing address of the incorporator are as follows:

            Name:             Steven Gelles
            Mailing Address:  122 East 42nd Street, Suite 606
            Zip Code:         New York, New York 10168

I, THE UNDERSIGNED, for the purpose of forming a Corporation under the laws of
the State of Delaware, do make, file and record this Certificate, and do
certify that the facts herein stated are true, and I have accordingly hereto
set my hand this Tenth day of March, 1983.


                                          /s/ Steven Gelles
- ----------------------------              ------------------------------

- ----------------------------