EXHIBIT A



                                 ENTREMED, INC.

                   AMENDED AND RESTATED 1996 STOCK OPTION PLAN


1.       PURPOSE.
         --------

         The purpose of this plan (the "Plan") is to secure for
ENTREMED, INC. (the "Company") and its shareholders the benefits arising from
capital stock ownership by employees, officers and directors of, and consultants
or advisors to, the Company who are expected to contribute to the Company's
future growth and success. Except where the context otherwise requires, the term
"Company" shall include all present and future subsidiaries of the Company as
defined in Sections 424(e) and 424(f) of the Internal Revenue Code of 1986, as
amended or replaced from time to time (the "Code"). Those provisions of the Plan
which make express reference to Section 422 of the Code shall apply only to
Incentive Stock Options (as that term is defined in the Plan).

2.       TYPE OF OPTIONS AND ADMINISTRATION.
         -----------------------------------

         (a) TYPES OF OPTIONS. Options granted pursuant to the Plan
shall be authorized by action of the Board of Directors of the Company (or a
committee designated by the Board of Directors) and may be either incentive
stock options ("Incentive Stock Options") meeting the requirements of Section
422 of the Code or non-statutory options which are not intended to meet the
requirements of Section 422 of the Code.

         (b) ADMINISTRATION. The Plan will be administered by a
committee (the "Committee") appointed by the Board of Directors of the Company,
whose construction and interpretation of the terms and provisions of the Plan
shall be final and conclusive. The delegation of powers to the Committee shall
be consistent with applicable laws or regulations (including, without
limitation, applicable state law and Rule 16b-3 ("Rule 16b-3") promulgated under
the Securities Exchange Act of 1934 (the "Exchange Act"), or any successor
rule). The Committee may in its sole discretion grant options to purchase shares
of the Company's Common Stock, $.01 par value per share ("Common Stock") and
issue shares upon exercise of such options as provided in the Plan. The
Committee shall have authority, subject to the express provisions of the Plan,
to construe the respective option agreements and the Plan, to prescribe, amend
and rescind rules and regulations relating to the Plan, to determine the terms
and provisions of the respective option agreements, which need not be identical,
and to make all other determinations in the judgment of the Committee necessary
or desirable for the administration of the Plan. The Committee may correct any
defect or supply any omission or reconcile any inconsistency in the Plan or in
any option agreement in the manner and to the extent it shall deem expedient to
carry the Plan into effect and it shall be the sole and final judge of such
expediency. No director or person acting pursuant to authority delegated by the
Board of Directors shall be liable for any action or determination under the
Plan made in good faith.  Subject to adjustment as provided in Section 15  

                                       1




below, the aggregate number of shares of Common Stock that may be subject to 
options granted to any person in a calendar year shall not exceed 25% of the 
maximum number of shares which may be issued and sold under the Plan, as set 
forth in Section 4 hereof, as such section may be amended from time to time.

         (c) APPLICABILITY OF RULE 16B-3. Those provisions of the Plan
which make express reference to Rule 16b-3 shall apply to the Company only at
such time as the Company's Common Stock is registered under the Exchange Act,
subject to the last sentence of Section 3(b), and then only to such persons as
are required to file reports under Section 16(a) of the Exchange Act (a
"Reporting Person").

3.       ELIGIBILITY.
         ------------

         (a) GENERAL. Options may be granted to persons who are, at the
time of grant, employees, officers or directors of, or consultants or advisors
to, the Company or any subsidiaries of the Company as defined in Sections 424(e)
and 424(f) of the Code ("Participants") PROVIDED, that Incentive Stock Options
may only be granted to individuals who are employees of the Company (within the
meaning of Section 3401(c) of the Code). A person who has been granted an option
may, if he or she is otherwise eligible, be granted additional options if the
Committee shall so determine.

         (b) GRANT OF OPTIONS TO REPORTING PERSONS. The selection of a
director or an officer who is a Reporting Person (as the terms "director" and
"officer" are defined for purposes of Rule 16b-3) as a recipient of an option,
the timing of the option grant, the exercise price of the option and the number
of shares subject to the option shall be determined in advance of the grant
either (i) by the Board of Directors or (ii) by a committee consisting of two or
more directors having full authority to act in the matter, each of whom shall be
a "non-employee director" (as hereinafter defined). For the purposes of the
Plan, a director shall be deemed to be a "non-employee director" only if such
person qualifies as a "non-employee director" within the meaning of Rule 16b-3,
as such term is interpreted from time to time.

         (c) DIRECTORS' OPTIONS. Commencing on the date this plan is
adopted by the Board of Directors, directors of the Company ("Eligible
Directors") will be granted an option (a "Director Option") to purchase 15,000
shares of Common Stock on the date that such person is first elected or
appointed a director ("Initial Director Option"). Commencing on the day
immediately following the date of the annual meeting of stockholders for the
Company's fiscal year ending December 31, 1996, (i) each Eligible Director will
receive an automatic grant of a Director Option to purchase 5,000 shares of
Common Stock, (ii) each member of any committee of the Board of Directors, other
than the Executive Committee, will receive an automatic grant of a Director
Option to purchase 1,000 shares of Common Stock and (iii) each member of the
Executive Committee of the Board of Directors will receive an automatic grant of
a Director Option to purchase 5,000 shares of Common Stock (each, an "Automatic
Grant") on the day immediately following the date of each annual meeting of
stockholders, as long as such director is a member of the Board of Directors.
The exercise price for each share subject to a Director Option shall be 

                                        2



equal to the fair market value of the Common Stock on the date of grant.
Director Options shall be exercisable commencing on the date the option is
granted and will expire the earlier of 10 years after the date of grant, unless
such Director Option is an Incentive Stock Option in which case such Director
Option shall be subject to the additional terms and conditions set forth in
Section 11.

4.       STOCK SUBJECT TO PLAN.
         ----------------------

         The stock subject to options granted under the Plan shall be
shares of authorized but unissued or reacquired Common Stock. Subject to
adjustment as provided in Section 15 below, the maximum number of shares of
Common Stock of the Company which may be issued and sold under the Plan is
1,266,667 shares. If an option granted under the Plan shall expire, terminate or
is cancelled for any reason without having been exercised in full, the
unpurchased shares subject to such option shall again be available for
subsequent option grants under the Plan.

5.       FORMS OF OPTION AGREEMENTS.
         ---------------------------

         As a condition to the grant of an option under the Plan, each
recipient of an option shall execute an option agreement in such form not
inconsistent with the Plan as may be approved by the Board of Directors. Such
option agreements may differ among recipients.

6.       PURCHASE PRICE.
         ---------------

         (a) GENERAL. The purchase price per share of stock deliverable
upon the exercise of an option shall be determined by the Board of Directors at
the time of grant of such option; PROVIDED, HOWEVER, that in the case of an
Incentive Stock Option, the exercise price shall not be less than 100% of the
Fair Market Value (as hereinafter defined) of such stock, at the time of grant
of such option, or less than 110% of such Fair Market Value in the case of
options described in Section 11(b). "Fair Market Value" of a share of Common
Stock of the Company as of a specified date for the purposes of the Plan shall
mean the closing price of a share of the Common Stock on the principal
securities exchange (including the Nasdaq National Market) on which such shares
are traded on the day immediately preceding the date as of which Fair Market
Value is being determined, or on the next preceding date on which such shares
are traded if no shares were traded on such immediately preceding day, or if the
shares are not traded on a securities exchange, Fair Market Value shall be
deemed to be the average of the high bid and low asked prices of the shares in
the over-the-counter market on the day immediately preceding the date as of
which Fair Market Value is being determined or on the next preceding date on
which such high bid and low asked prices were recorded. If the shares are not
publicly traded, Fair Market Value of a share of Common Stock (including, in the
case of any repurchase of shares, any distributions with respect thereto which
would be repurchased with the shares) shall be determined in good faith by the
Board of Directors. In no case shall Fair Market Value be determined with regard
to restrictions other than restrictions which, by their terms, will never lapse.

                                        3



         (b) PAYMENT OF PURCHASE PRICE. Options granted under the Plan
may provide for the payment of the exercise price by delivery of cash or a check
to the order of the Company in an amount equal to the exercise price of such
options, or by any other means which the Board of Directors determines are
consistent with the purpose of the Plan and with applicable laws and regulations
(including, without limitation, the provisions of Rule 16b-3 and Regulation T
promulgated by the Federal Reserve Board).

7.       OPTION PERIOD.
         --------------

         Subject to earlier termination as provided in the Plan, each
option and all rights thereunder shall expire on such date as determined by the
Board of Directors and set forth in the applicable option agreement, PROVIDED,
that such date shall not be later than (10) ten years after the date on which
the option is granted.

8.       EXERCISE OF OPTIONS.
         --------------------

         Each option granted under the Plan shall be exercisable either
in full or in installments at such time or times and during such period as shall
be set forth in the option agreement evidencing such option, subject to the
provisions of the Plan. Subject to the requirements in the immediately preceding
sentence, if an option is not at the time of grant immediately exercisable, the
Board of Directors may (i) in the agreement evidencing such option, provide for
the acceleration of the exercise date or dates of the subject option upon the
occurrence of specified events, and/or (ii) at any time prior to the complete
termination of an option, accelerate the exercise date or dates of such option.

9.       TRANSFERABILITY OF OPTIONS.
         ---------------------------

         No incentive stock option granted under this Plan shall be
assignable or otherwise transferable by the optionee except by will or by the
laws of descent and distribution or pursuant to a qualified domestic relations
order as defined in the Code or Title I of the Employee Retirement Income
Security Act, or the rules thereunder. The Board of Directors or any committee
thereof may, in its discretion, authorize all or a portion of any non-statutory
options to be granted to an optionee to be on terms which permit transfer by
such optionee to (i) the spouse, children or grandchildren of the optionee
("Immediate Family Members"), (ii) a trust or trusts for the exclusive benefit
of such Immediate Family Members, (iii) a partnership in which such Immediate
Family Members are the only partners or (iv) any non-profit charitable
organization; provided that (w) the options must be held by the optionee for a
period of at least one month prior to transfer, (x) there may be no
consideration for any such transfer, (y) the stock option agreement pursuant to
which such options are granted must be approved by the Committee, and must
expressly provide for transferability in a manner consistent with this Section,
and (z) subsequent transfers of transferred options shall be prohibited except
by will or the laws of descent and distribution or pursuant to a qualified
domestic relations order as defined in the Code or Title I of the Employee 

                                        4



Retirement Income Security Act, or the rules thereunder. Following transfer, 
any such options shall continue to be subject to the same terms and conditions 
as were applicable immediately prior to transfer, provided that for purposes of 
the Plan the term "optionee" shall be deemed to refer to the transferee. The 
events of termination of employment of Section 10 hereof shall continue to be 
applied with respect to the original optionee. In the event an optionee dies 
during his employment by the Company or any of its subsidiaries, or during the 
three-month period following the date of termination of such employment, his 
option shall thereafter be exercisable, during the period specified in the 
option agreement, by his executors or administrators to the full extent to 
which such option was exercisable by the optionee at the time of his death 
during the periods set forth in Section 10 or 11(d).

10.      FFECT OF TERMINATION OF EMPLOYMENT OR OTHER RELATIONSHIP.
         ---------------------------------------------------------

         xcept as provided in Section 11(d) with respect to Incentive
Stock Options and except as otherwise determined by the Committee at the date of
grant of an option, and subject to the provisions of the Plan, an optionee may
exercise an option at any time within three (3) months following the termination
of the optionee's employment or other relationship with the Company or within
one (1) year if such termination was due to the death or disability of the
optionee but, except in the case of the optionee's death, in no event later than
the expiration date of the option. If the termination of the optionee's
employment is for cause or is otherwise attributable to a breach by the optionee
of an employment or confidentiality or non-disclosure agreement, the option
shall expire immediately upon such termination. The Board of Directors shall
have the power to determine what constitutes a termination for cause or a breach
of an employment or confidentiality or non-disclosure agreement, whether an
optionee has been terminated for cause or has breached such an agreement, and
the date upon which such termination for cause or breach occurs. Any such
determinations shall be final and conclusive and binding upon the optionee.

11.      INCENTIVE STOCK OPTIONS.
         ------------------------

         Options granted under the Plan which are intended to be
Incentive Stock Options shall be subject to the following additional terms and
conditions:

         (a)  EXPRESS DESIGNATION.  All Incentive Stock Options granted under 
the Plan shall, at the time of grant, be specifically designated as such in the 
option agreement covering such Incentive Stock Options.

         (b) 10% SHAREHOLDER. If any employee to whom an Incentive
Stock Option is to be granted under the Plan is, at the time of the grant of
such option, the owner of stock possessing more than 10% of the total combined
voting power of all classes of stock of the Company (after taking into account
the attribution of stock ownership rules of Section 424(d) of the Code), then
the following special provisions shall be applicable to the Incentive Stock
Option granted to such individual:

                                        5



                         (i)      The purchase price per share of the Common 
         Stock subject to such Incentive Stock Option shall not be less than 
         110% of the Fair Market Value of one share of Common Stock at the 
         time of grant; and

                         (ii)     The option exercise period shall not exceed 
         five years from the date of grant.

         (c) DOLLAR LIMITATION. For so long as the Code shall so
provide, options granted to any employee under the Plan (and any other incentive
stock option plans of the Company) which are intended to constitute Incentive
Stock Options shall not constitute Incentive Stock Options to the extent that
such options, in the aggregate, become exercisable for the first time in any one
calendar year for shares of Common Stock with an aggregate Fair Market Value, as
of the respective date or dates of grant, of more than $100,000.

         (d) TERMINATION OF EMPLOYMENT, DEATH OR DISABILITY. No
Incentive Stock Option may be exercised unless, at the time of such exercise,
the optionee is, and has been continuously since the date of grant of his or her
option, employed by the Company, except that:

                       (i) an Incentive Stock Option may be exercised
         within the period of three months after the date the optionee
         ceases to be an employee of the Company (or within such lesser
         period as may be specified in the applicable option
         agreement), PROVIDED, that the agreement with respect to such
         option may designate a longer exercise period and that the
         exercise after such three-month period shall be treated as the
         exercise of a non-statutory option under the Plan;

                      (ii) if the optionee dies while in the employ of
         the Company, or within three months after the optionee ceases
         to be such an employee, the Incentive Stock Option may be
         exercised by the person to whom it is transferred by will or
         the laws of descent and distribution within the period of one
         year after the date of death (or within such lesser period as
         may be specified in the applicable option agreement); and

                     (iii) if the optionee becomes disabled (within the
         meaning of Section 22(e)(3) of the Code or any successor
         provisions thereto) while in the employ of the Company, the
         Incentive Stock Option may be exercised within the period of
         one year after the date the optionee ceases to be such an
         employee because of such disability (or within such lesser
         period as may be specified in the applicable option
         agreement).

For all purposes of the Plan and any option granted hereunder, "employment"
shall be defined in accordance with the provisions of Section 1.421-7(h) of the
Income Tax Regulations (or any successor regulations). Notwithstanding the
foregoing provisions, no Incentive Stock Option may be exercised after its
expiration date.


                                        6



12.      ADDITIONAL PROVISIONS.
         ----------------------

         (a) ADDITIONAL OPTION PROVISIONS. The Board of Directors may,
in its sole discretion, include additional provisions in option agreements
covering options granted under the Plan, including without limitation
restrictions on transfer, repurchase rights, rights of first refusal,
commitments to pay cash bonuses, to make, arrange for or guaranty loans or to
transfer other property to optionees upon exercise of options, or such other
provisions as shall be determined by the Board of Directors; PROVIDED, that such
additional provisions shall not be inconsistent with any other term or condition
of the Plan and such additional provisions shall not cause any Incentive Stock
Option granted under the Plan to fail to qualify as an Incentive Stock Option
within the meaning of Section 422 of the Code.

         (b) ACCELERATION, EXTENSION, ETC. The Board of Directors may,
in its sole discretion, (i) accelerate the date or dates on which all or any
particular option or options granted under the Plan may be exercised or (ii)
extend the dates during which all, or any particular, option or options granted
under the Plan may be exercised; PROVIDED, HOWEVER, that no such extension shall
be permitted if it would cause the Plan to fail to comply with Section 422 of
the Code or with Rule 16b-3 (if applicable).

13.      GENERAL RESTRICTIONS.
         ---------------------

         (a) INVESTMENT REPRESENTATIONS. The Company may require any
person to whom an option is granted, as a condition of exercising such option,
to give written assurances in substance and form satisfactory to the Company to
the effect that such person is acquiring the Common Stock subject to the option
or award, for his or her own account for investment and not with any present
intention of selling or otherwise distributing the same, and to such other
effects as the Company deems necessary or appropriate in order to comply with
federal and applicable state securities laws, or with covenants or
representations made by the Company in connection with any public offering of
its Common Stock, including any "lock-up" or other restriction on
transferability.

         (b) COMPLIANCE WITH SECURITIES LAW. Each option shall be
subject to the requirement that if, at any time, counsel to the Company shall
determine that the listing, registration or qualification of the shares subject
to such option or award upon any securities exchange or automated quotation
system or under any state or federal law, or the consent or approval of any
governmental or regulatory body, or that the disclosure of non-public
information or the satisfaction of any other condition is necessary as a
condition of, or in connection with the issuance or purchase of shares
thereunder, such option or award may not be exercised, in whole or in part,
unless such listing, registration, qualification, consent or approval, or
satisfaction of such condition shall have been effected or obtained on
conditions acceptable to the Board of Directors. Nothing herein shall be deemed
to require the Company to apply for or to obtain such listing, registration or
qualification, or to satisfy such condition.


                                        7



14.      RIGHTS AS A SHAREHOLDER.
         ------------------------

         The holder of an option shall have no rights as a shareholder
with respect to any shares covered by the option (including, without limitation,
any rights to receive dividends or non-cash distributions with respect to such
shares) until the date of issue of a stock certificate to him or her for such
shares. No adjustment shall be made for dividends or other rights for which the
record date is prior to the date such stock certificate is issued.

15.      ADJUSTMENT PROVISIONS FOR RECAPITALIZATIONS, REORGANIZATIONS AND 
         RELATED TRANSACTIONS.
         ----------------------------------------------------------------

         (a) RECAPITALIZATIONS AND RELATED TRANSACTIONS. If, through or
as a result of any recapitalization, reclassification, stock dividend, stock
split, reverse stock split or other similar transaction, (i) the outstanding
shares of Common Stock are increased, decreased or exchanged for a different
number or kind of shares or other securities of the Company, or (ii) additional
shares or new or different shares or other non-cash assets are distributed with
respect to such shares of Common Stock or other securities, an appropriate and
proportionate adjustment shall be made in (x) the maximum number and kind of
shares reserved for issuance under or otherwise referred to in the Plan, (y) the
number and kind of shares or other securities subject to any then outstanding
options under the Plan, and (z) the price for each share subject to any then
outstanding options under the Plan, without changing the aggregate purchase
price as to which such options remain exercisable. Notwithstanding the
foregoing, no adjustment shall be made pursuant to this Section 15 if such
adjustment (i) would cause the Plan to fail to comply with Section 422 of the
Code or with Rule 16b-3 or (ii) would be considered as the adoption of a new
plan requiring stockholder approval.

         (b) REORGANIZATION, MERGER AND RELATED TRANSACTIONS. All
outstanding options under the Plan shall become fully exercisable for a period
of sixty (60) days following the occurrence of any Trigger Event, whether or not
such options are then exercisable under the provisions of the applicable
agreements relating thereto. For purposes of the Plan, a "Trigger Event" is any
one of the following events:

                         (i) the date on which shares of Common Stock
         are first purchased pursuant to a tender offer or exchange
         offer (other than such an offer by the Company, any
         Subsidiary, any employee benefit plan of the Company or of any
         Subsidiary or any entity holding shares or other securities of
         the Company for or pursuant to the terms of such plan),
         whether or not such offer is approved or opposed by the
         Company and regardless of the number of shares purchased
         pursuant to such offer;

                         (ii) the date the Company acquires knowledge
         that any person or group deemed a person under Section 13(d)-3
         of the Exchange Act (other than the Company, any Subsidiary,
         any employee benefit plan of the Company or of any Subsidiary
         or any entity holding shares of Common Stock or other
         securities of the Company for or pursuant to the terms of any 

                                        8



         such plan or any individual or entity or group or affiliate 
         thereof which acquired its beneficial ownership interest prior 
         to the date the Plan was adopted by the Board), in a transaction 
         or series of transactions, has become the beneficial owner, 
         directly or indirectly (with beneficial ownership determined as 
         provided in Rule 13d-3, or any successor rule, under the Exchange 
         Act), of securities of the Company entitling the person or group 
         to 30% or more of all votes (without consideration of the rights
         of any class or stock to elect directors by a separate class
         vote) to which all shareholders of the Company would be
         entitled in the election of the Board of Directors were an
         election held on such date;

                         (iii) the date, during any period of two
         consecutive years, when individuals who at the beginning of
         such period constitute the Board of Directors of the Company
         cease for any reason to constitute at least a majority
         thereof, unless the election, or the nomination for election
         by the shareholders of the Company, of each new director was
         approved by a vote of at least two-thirds of the directors
         then still in office who were directors at the beginning of
         such period; and

                         (iv)     the date of approval by the shareholders of 
         the Company of an agreement (a "reorganization agreement") providing 
         for:

                         (A) The merger of consolidation of the Company
                  with another corporation where the shareholders of
                  the Company, immediately prior to the merger or
                  consolidation, do not beneficially own, immediately
                  after the merger or consolidation, shares of the
                  corporation issuing cash or securities in the merger
                  or consolidation entitling such shareholders to 65%
                  or more of all votes (without consideration of the
                  rights of any class of stock to elect directors by a
                  separate class vote) to which all shareholders of
                  such corporation would be entitled in the election of
                  directors or where the members of the Board of
                  Directors of the Company, immediately prior to the
                  merger or consolidation, do not, immediately after
                  the merger or consolidation, constitute a majority of
                  the Board of Directors of the corporation issuing
                  cash or securities in the merger or consolidation; or

                         (B) The sale or other disposition of all or
                  substantially all the assets of the Company.

         (c) BOARD AUTHORITY TO MAKE ADJUSTMENTS. Any adjustments under
this Section 15 will be made by the Board of Directors, whose determination as
to what adjustments, if any, will be made and the extent thereof will be final,
binding and conclusive. No fractional shares will be issued under the Plan on
account of any such adjustments.


                                        9



16.      MERGER, CONSOLIDATION, ASSET SALE, LIQUIDATION, ETC.
         ----------------------------------------------------

         (a) GENERAL. In the event of any sale, merger, transfer or
acquisition of the Company or substantially all of the assets of the Company in
which the Company is not the surviving corporation, and provided that after the
Company shall have requested the acquiring or succeeding corporation (or an
affiliate thereof), that equivalent options shall be substituted and such
successor corporation shall have refused or failed to assume all options
outstanding under the Plan or issue substantially equivalent options, then any
or all outstanding options under the Plan shall accelerate and become
exercisable in full immediately prior to such event. The Committee will notify
holders of options under the Plan that any such options shall be fully
exercisable for a period of fifteen (15) days from the date of such notice, and
the options will terminate upon expiration of such notice.

         (b) SUBSTITUTE OPTIONS. The Company may grant options under
the Plan in substitution for options held by employees of another corporation
who become employees of the Company, or a subsidiary of the Company, as the
result of a merger or consolidation of the employing corporation with the
Company or a subsidiary of the Company, or as a result of the acquisition by the
Company, or one of its subsidiaries, of property or stock of the employing
corporation. The Company may direct that substitute options be granted on such
terms and conditions as the Board of Directors considers appropriate in the
circumstances.

17.      NO SPECIAL EMPLOYMENT RIGHTS.
         -----------------------------

         Nothing contained in the Plan or in any option shall confer
upon any optionee any right with respect to the continuation of his or her
employment by the Company or interfere in any way with the right of the Company
at any time to terminate such employment or to increase or decrease the
compensation of the optionee.

18.      OTHER EMPLOYEE BENEFITS.
         ------------------------

         Except as to plans which by their terms include such amounts
as compensation, the amount of any compensation deemed to be received by an
employee as a result of the exercise of an option or the sale of shares received
upon such exercise will not constitute compensation with respect to which any
other employee benefits of such employee are determined, including, without
limitation, benefits under any bonus, pension, profit-sharing, life insurance or
salary continuation plan, except as otherwise specifically determined by the
Board of Directors.

19.      AMENDMENT OF THE PLAN.
         ----------------------

         (a) The Board of Directors may at any time, and from time to
time, modify or amend the Plan in any respect; provided, however, that if at any
time the approval of the shareholders of the Company is required under Section
422 of the Code or any successor provision with respect to Incentive Stock
Options, or under Rule 16b-3, the Board of Directors may not effect such 
modification or amendment without such approval.


                                       10



         (b) The modification or amendment of the Plan shall not,
without the consent of an optionee, affect his or her rights under an option
previously granted to him or her. With the consent of the optionee affected, the
Board of Directors may amend outstanding option agreements in a manner not
inconsistent with the Plan. The Board of Directors shall have the right to amend
or modify (i) the terms and provisions of the Plan and of any outstanding
Incentive Stock Options granted under the Plan to the extent necessary to
qualify any or all such options for such favorable federal income tax treatment
(including deferral of taxation upon exercise) as may be afforded incentive
stock options under Section 422 of the Code and (ii) the terms and provisions of
the Plan and of any outstanding option to the extent necessary to ensure the
qualification of the Plan under Rule 16b-3.

20.      WITHHOLDING.
         ------------

         (a) The Company shall have the right to deduct from payments
of any kind otherwise due to the optionee any federal, state or local taxes of
any kind required by law to be withheld with respect to any shares issued upon
exercise of options under the Plan. Subject to the prior approval of the
Company, which may be withheld by the Company in its sole discretion, the
optionee may elect to satisfy such obligations, in whole or in part, (i) by
causing the Company to withhold shares of Common Stock otherwise issuable
pursuant to the exercise of an option or (ii) by delivering to the Company
shares of Common Stock already owned by the optionee. The shares so delivered or
withheld shall have a Fair Market Value equal to such withholding obligation as
of the date that the amount of tax to be withheld is to be determined. An
optionee who has made an election pursuant to this Section 20(a) may only
satisfy his or her withholding obligation with shares of Common Stock which are
not subject to any repurchase, forfeiture, unfulfilled vesting or other similar
requirements.

         (b) The acceptance of shares of Common Stock upon exercise of
an Incentive Stock Option shall constitute an agreement by the optionee (i) to
notify the Company if any or all of such shares are disposed of by the optionee
within two years from the date the option was granted or within one year from
the date the shares were issued to the optionee pursuant to the exercise of the
option, and (ii) if required by law, to remit to the Company, at the time of and
in the case of any such disposition, an amount sufficient to satisfy the
Company's federal, state and local withholding tax obligations with respect to
such disposition, whether or not, as to both (i) and (ii), the optionee is in
the employ of the Company at the time of such disposition.

         (c) Notwithstanding the foregoing, in the case of a Reporting
Person whose options have been granted in accordance with the provisions of
Section 3(b) herein, no election to use shares for the payment of withholding
taxes shall be effective unless made in compliance with any applicable
requirements of Rule 16b-3.


                                       11



21.      CANCELLATION AND NEW GRANT OF OPTIONS, ETC.
         -------------------------------------------

         The Board of Directors shall have the authority to effect, at
any time and from time to time, with the consent of the affected optionees, (i)
the cancellation of any or all outstanding options under the Plan and the grant
in substitution therefor of new options under the Plan covering the same or
different numbers of shares of Common Stock and having an option exercise price
per share which may be lower or higher than the exercise price per share of the
cancelled options or (ii) the amendment of the terms of any and all outstanding
options under the Plan to provide an option exercise price per share which is
higher or lower than the then-current exercise price per share of such
outstanding options.

22.      EFFECTIVE DATE AND DURATION OF THE PLAN.
         ----------------------------------------

         (a) EFFECTIVE DATE. The Plan shall become effective when
adopted by the Board of Directors, but no Incentive Stock Option granted under
the Plan shall become exercisable unless and until the Plan shall have been
approved by the Company's shareholders. If such shareholder approval is not
obtained within twelve months after the date of the Board's adoption of the
Plan, no options previously granted under the Plan shall be deemed to be
Incentive Stock Options and no Incentive Stock Options shall be granted
thereafter. Amendments to the Plan not requiring shareholder approval shall
become effective when adopted by the Board of Directors; amendments requiring
shareholder approval (as provided in Section 21) shall become effective when
adopted by the Board of Directors, but no Incentive Stock Option granted after
the date of such amendment shall become exercisable (to the extent that such
amendment to the Plan was required to enable the Company to grant such Incentive
Stock Option to a particular optionee) unless and until such amendment shall
have been approved by the Company's shareholders. If such shareholder approval
is not obtained within twelve months of the Board's adoption of such amendment,
any Incentive Stock Options granted on or after the date of such amendment shall
terminate to the extent that such amendment to the Plan was required to enable
the Company to grant such option to a particular optionee. Subject to this
limitation, options may be granted under the Plan at any time after the
effective date and before the date fixed for termination of the Plan.

         (b) TERMINATION. Unless sooner terminated in accordance with
Section 16, the Plan shall terminate upon the earlier of (i) the close of
business on the day next preceding the tenth anniversary of the date of its
adoption by the Board of Directors, or (ii) the date on which all shares
available for issuance under the Plan shall have been issued pursuant to the
exercise or cancellation of options granted under the Plan. If the date of
termination is determined under (i) above, then options outstanding on such date
shall continue to have force and effect in accordance with the provisions of the
instruments evidencing such options.

23.      PROVISION FOR FOREIGN PARTICIPANTS.
         -----------------------------------

         The Board of Directors may, without amending the Plan, modify
awards or options granted to participants who are foreign nationals or employed
outside the United States to recognize differences in laws, rules, regulations 
or customs of such foreign jurisdictions with respect to tax, securities, 
currency, employee benefit or other matters.

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24.      GOVERNING LAW.
         --------------

         The provisions of this Plan shall be governed and construed in
accordance with the laws of the State of Delaware without regard to the
principles of conflicts of laws.

         Adopted by the Board of Directors on March 29, 1996, amended
and restated on May 7, 1996 and further amended and restated on April __, 1997.

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