<PAGE>

                                CETUS CORPORATION
                    Amended and Restated Common Stock Option Plan
                           NONSTATUTORY OPTION AGREEMENT


To:

This is to inform you that, under Cetus Corporation's (the "Company") Amended 
and Restated Common Stock Option Plan (the "Plan"), the Company has granted 
to you a nonstatutory stock option to purchase shares of the Company's Common 
Stock (the "Common Stock").  Certain information about this option, including 
the number of shares of Common Stock covered by the option, is set forth on 
the "Summary Information Sheet" attached to this agreement as EXHIBIT A. This 
agreement is intended to formally describe and record other terms and 
conditions of this option grant.  Capitalized terms used but not defined in 
this agreement have the meanings given them in the Plan; a copy of the Plan 
is attached to this agreement as EXHIBIT B.

ACCORDINGLY, YOU AND THE COMPANY AGREE AS FOLLOWS:

1.   VESTING AND EXPIRATION OF OPTION.  In order to exercise this option, you
     must remain in the employ of the Company until the Vesting Date on which 
     this option becomes wholly or partially exercisable.  This option shall 
     become exercisable at the times, and with respect to the number of shares,
     set forth on the Summary Information Sheet.

     Exercisability of this option may also be accelerated or adjusted as
     provided in the Plan or in this agreement.  This option expires ten years
     after the date it was granted (the "Expiration Date").  If you do not
     exercise each portion of the option on the earliest Vesting Date on which
     it becomes exercisable, then (subject to the other provisions of this
     agreement) you may exercise that portion, in whole or in part, at any time
     prior to the Expiration Date.  For the purposes of this Agreement, "employ"
     and "employment" shall include services as a Consultant or Officer of the
     Company.

2.   EXERCISE OF OPTION.  This option shall be exercised by notice in writing,
     signed by you or the person authorized to exercise this option under 
     paragraph 5, and delivered or mailed by registered or certified mail to 
     the Company at its general office in Emeryville, California, Attention: 
     Treasurer.  The notice shall state the number of shares with respect to 
     which you are exercising the option and must be accompanied by payment 
     of the total option price of the shares being purchased.

3.   PAYMENT OF OPTION PRICE.  The option price for the purchase of shares of
     Common Stock covered by this option is the price specified on the Summary
     Information Sheet.  Payment in full shall be made for all shares being
     purchased upon exercise of an option.  Payment may be made in cash, by
     check or by shares of Common Stock of the Company endorsed in favor of the
     Company or accompanied by a blank stock power, or any combination of the
     above.  You may pay the option price with shares of Common Stock of the
     Company only once in any six-month period.  Any Common Stock delivered to
     the Company as payment for shares upon exercise of the option shall be
     valued at its fair market value, determined by the closing bid price on the
     date of exercise of the option.

<PAGE>

4.   NON-ASSIGNABILITY OF OPTION.  Except for a limited exception set forth 
     in the Plan, you may not assign or transfer this option except by will 
     or by the laws of descent and distribution, and only you may exercise 
     this option during your lifetime.

5.   EXERCISE AFTER TERMINATION OF EMPLOYMENT OR DEATH.  If your employment by
     the Company is terminated for any reason other than death or permanent and
     total disability, you may exercise this option, as to all or any of the
     shares you were entitled to purchase at the date of termination, at any
     time within three months after the date of such termination (but in no
     event after the Expiration Date), but not thereafter.  If you die or become
     permanently or totally disabled while employed by the company (or, in the
     case of death, within three months of termination of employment), your
     personal representative, heirs or legatees may exercise this option, with
     respect to all or any of the shares which you were entitled to purchase
     immediately prior to your death or disability, at any time within one year
     after your death or disability (but in no event after the Expiration Date),
     but not thereafter.

6.   DELIVERY OF SHARES.  The Company shall not be obligated to deliver any
     shares upon exercise of this option until all Federal and state laws and 
     regulations which the Company may determine are applicable have been 
     complied with.  If shares to be delivered are not registered under the 
     Securities Act of 1933, as amended, you agree to represent that such shares
     are being acquired for investment and not with a view to the sale or 
     distribution thereof, and shall make such other representations deemed 
     necessary by counsel to the Company.  Stock certificates evidencing 
     unregistered shares acquired upon exercise of this option shall bear a 
     restrictive legend as follows:

          These securities have not been registered under the  Securities
          Act of 1933 and may not be transferred or resold without
          registration under the Act unless in the opinion of counsel to
          the issuer an exemption from registration is then available.

7.   ADJUSTMENT OF SHARES.  If the number of outstanding shares of Common Stock
     of the Company is hereafter increased or decreased, or changed into or 
     exchanged for a different number or kind of shares or other securities of 
     the Company or of another corporation, by reason of a reorganization, 
     merger, consolidation, recapitalization, reclassification, stock split, 
     combination of shares or declaration of stock dividends, the number and/or
     kind of shares covered by this option shall be adjusted proportionately by
     the Administrator of the Plan.  Any adjustment shall be made without 
     change in the total exercise price applicable to the unexercised portion of
     this option and with a corresponding adjustment in the exercise price per 
     share. Any adjustment under this Section 7 shall be subject to the 
     provisions of the Company's Amended and Restated Certificate of 
     Incorporation, as amended, and applicable law.

<PAGE>

8.   ACCELERATION OF VESTING.  In the event of a Change of Control (as 
     defined in the Plan) or upon the Sale of Significant Assets (as 
     described below), this option shall become exercisable with respect to 
     100% of the number of shares of Common Stock covered by this option, 
     unless the Company's Board of Directors, on the basis of those factors 
     it considers relevant, including the effects on stockholders and option 
     holders, specifically determines that full acceleration would not be in 
     the best interests of the Company.  If the board makes such a 
     determination, as a minimum, this option will vest on a pro-rated 
     monthly basis to the date of such event, according to the percentages 
     set forth on the Summary Information Sheet, plus an additional twelve 
     months (also pro-rated monthly).

     With respect to a "Sale of Significant Assets", the acceleration of this
     option under this paragraph would be triggered by a sale or sales of
     portions of the Company's business in any six-month period for cash in an
     aggregate amount of $100 million or more.  Other dispositions of assets
     (for example, a transfer to a joint venture or other corporation or
     partnership in exchange for an interest in the venture or entity, a
     licensing arrangement, a sale-and-leaseback transaction or a sale of real
     property) would not be covered by this paragraph.

9.  STOCKHOLDER'S RIGHTS.  You will have no rights as a stockholder by virtue of
    this option except with respect to shares actually issued to you, and 
    issuance of shares shall confer no retroactive right to dividends or other 
    stockholder rights.

10. FEDERAL INCOME TAX.  The tax consequences associated with this option and
    shares purchased under this option are complex and can depend in part on 
    your particular circumstances.  You should understand, for example, that
    generally you will recognize income when the option is exercised, even
    before you resell the stock purchased.  Also, shares acquired on exercise of
    a nonstatutory option which are subject to a repurchase right or other
    substantial risk of forfeiture will be subject to the special rules of
    section 83 of the Internal Revenue Code.  In some such cases, it may be
    desirable to make a special election under section 83(b) within 30 days
    after you exercise your option.  Also, you should be aware that state and
    local income tax consequences may be quite different from the federal tax
    consequences.  For these reasons you should consult your tax advisor about
    possible tax consequences.

     The Company may withhold from your paycheck or require you to pay to the
     Company any amounts required by it to be withheld or paid under applicable
     tax requirements, including requirements resulting from the purchase of
     shares pursuant to this option.  Any such payment shall be made in cash or
     by check at the time of exercise.

11.  LIMITED STOCK APPRECIATION RIGHTS. If you are an officer of the Company who
     is subject to the "short swing" provisions of the Exchange Act of 1934, the
     Company has granted to you, in tandem with this option, limited stock
     appreciation rights ("Limited Right") equal in number to the number of
     shares covered by this option.  The terms and conditions governing the
     grant of this Limited Right are described in Section 10 of the Plan.

<PAGE>

12. ACCEPTANCE WAIVER.  By accepting this option, you accept and agree to be
    bound by each and all the terms and conditions of this agreement and of the
    Plan.  In case of any conflict between this agreement and the terms of the 
    Plan, the Plan shall control.  No waiver of any term or condition of the 
    agreement or the Plan shall be construed to be a waiver of any other term 
    or condition or to be a consent to any further waiver of the same or any 
    other term or condition.

13. BINDING EFFECT.  Subject to the limitations of this agreement, this
    agreement shall be binding on, and inure to the benefit of, the executors, 
    administrators, heirs, legal representatives, successors and assigns of the 
    parties hereto.



                                        CETUS CORPORATION
                                        
                                        By:
                                           --------------------------------

ACCEPTED

-----------------------------
Optionee

<PAGE>

                         NONSTATUTORY OPTION AGREEMENT



To:

     This is to inform you that Cetus Corporation (the "Company") granted to you
     on         , a nonstatutory option, under the Cetus Corporation Non-
     Employee Directors' Stock Option Plan (the "Plan"), to purchase a total of
          shares of the Company's Common Stock (the "Common Stock") at a price
     of $     per share on   , under the following terms and conditions:

1.   VESTING AND EXPIRATION OF OPTION.  In order to exercise this option, you
     must remain as a director of the Company until the Vesting Date on which 
     this option becomes wholly or partially exercisable.  This option shall 
     become exercisable with respect to the percentage of total shares covered 
     by the option as follows:

                                             Percentage of Shares
               Vesting Date                    Covered by Option
               ------------                  --------------------

                                                  33 1/3%
                                             an additional 33 1/3%
                                             an additional 33 1/3%


     Exercisability of this option may also be accelerated or adjusted as
     provided in the Plan or this agreement.  This option expires ten years
     after the date it was granted (the "Expiration Date").  If you do not
     exercise each portion of the option on the earliest Vesting Date on which
     it becomes exercisable, then (subject to the other provisions of this
     Agreement) you may exercise that portion, in whole or in part, at any time
     prior to the Expiration Date.

2.   EXERCISE OF OPTION.  This option shall be exercised by notice in writing,
     signed by you or the person authorized to exercise this option under 
     paragraph 5, and delivered or mailed by registered or certified mail to the
     Company at its general office in Emeryville, California, Attention: 
     Treasurer.  The notice shall state the number of shares with respect to 
     which you are exercising the option and must be accompanied by payment of 
     the total option price of the shares being purchased.

3.   PAYMENT OF OPTION PRICE.  Payment in full shall be made for all shares
     being purchased upon exercise of an option.  Payment may be made in cash, 
     by check or by shares of Common Stock of the Company endorsed in favor of 
     the Company or accompanied by a blank stock power, or any combination of 
     the above.  You may pay the option price with shares of Common Stock of the
     Company only once in any six-month period.  Any Common Stock delivered to
     the Company as payment for shares upon exercise of the option shall be
     valued at its fair market value, determined by the closing bid price on the
     date of exercise of the option.

<PAGE>

4.   NON-ASSIGNABILITY OF OPTION.  Except for a limited exception set forth in
     the Plan, you may not assign or transfer this option except by will or by 
     the laws of descent and distribution, and only you may exercise this option
     during your lifetime.

5.   EXERCISE AFTER TERMINATION OF EMPLOYMENT OR DEATH.  If your term as a
     director of the Company is terminated for any reason other than death or 
     permanent and total disability, you may exercise this option, as to all or
     any of the shares you were entitled to purchase at the date of termination,
     at any time within three months after the date of such termination (but in 
     no event after the Expiration Date), but not thereafter.  If you die or 
     become permanently or totally disabled while a director of the company 
     (or, in the case of death, within three months of the termination of your 
     term), your personal representative, heirs or legatees may exercise this 
     option, with respect to all or any of the shares which you were entitled to
     purchase immediately prior to your death or disability, at any time within 
     one year after your death or disability (but in no event after the 
     Expiration Date), but not thereafter.

6.   DELIVERY OF SHARES.  The Company shall not be obligated to deliver any
     shares upon exercise of this option until all Federal and state laws and 
     regulations which the Company may determine are applicable have been 
     complied with. If shares to be delivered are not registered under the 
     Securities Act of 1933, as amended, you agree to represent that such shares
     are being acquired for investment and not with a view to the sale or 
     distribution thereof, and shall make such other representations deemed 
     necessary by counsel to the Company. Stock certificates evidencing 
     unregistered shares acquired upon exercise of this option shall bear a 
     restrictive legend as follows:

          These securities have not been registered under the Securities
          Act of 1933 and may not be transferred or resold without
          registration under the Act unless in the opinion of counsel to
          the issuer an exemption from registration is then available.

7.   ADJUSTMENT OF SHARES.  If the number of outstanding shares of Common Stock
     of the Company is hereafter increased or decreased, or changed into or 
     exchanged for a different number or kind of shares or other securities of 
     the Company or of another corporation, by reason of a reorganization, 
     merger, consolidation, recapitalization, reclassification, stock split, 
     combination of shares or declaration of stock dividends, the number and/or 
     kind of shares covered by this option shall be adjusted proportionately by 
     the Administrator of the Plan.  Any adjustment shall be made without change
     in the total exercise price applicable to the unexercised portion of this
     option and with a corresponding adjustment in the exercise price per share.
     Any adjustment under this Paragraph 7 shall be subject to the provisions of
     the Company's Certificate of Incorporation, as then amended, and applicable
     law.

<PAGE>

8.   ACCELERATION OF VESTING.  In the event of a Change of Control (as defined
     in the Plan) or upon the Sale of Significant Assets (as described below), 
     this option shall become exercisable with respect to 100% of the number of
     shares of Common Stock covered by this option, unless the Company's Board
     of Directors, on the basis of those factors it considers relevant,
     including the effects on stockholders and option holders, specifically
     determines that full acceleration would not be in the best interest of the
     Company.  If the board makes such a determination, at a minimum, this
     option will vest on a pro-rated monthly basis to the date of such event,
     according to the percentages set forth in this agreement, plus an
     additional twelve months (also pro-rated monthly).

     With respect to a "Sale of Significant Assets", the acceleration of this
     option under this paragraph would be triggered by a sale or sales of
     portions of the Company's business in any six-month period for cash in an
     aggregate amount of $100 million or more.  Other dispositions of assets
     (for example, a transfer to a joint venture or other corporation or
     partnership in exchange for an interest in the venture or entity, a
     licensing arrangement, a sale-and-leaseback transaction or a sale of real
     property) would not be covered by this paragraph.

9.   STOCKHOLDER'S RIGHTS.  You will have no rights as a stockholder by virtue
     of this option except with respect to shares actually issued to you, and 
     issuance of shares shall confer no retroactive right to dividends or other
     stockholder rights.

10.  FEDERAL INCOME TAX.  The tax consequences associated with this option and
     shares purchased under this option are complex and can depend in part on 
     your particular circumstances.  You should understand, for example, that
     generally you will recognize income when the option is exercised, even
     before you resell the stock purchased.  Also, shares acquired on exercise
     of a nonstatutory option which are subject to a repurchase right or other
     substantial risk of forfeiture will be subject to the special rules of
     section 83 of the Internal Revenue Code.  In some such cases, it may be
     desirable to make a special election under section 83(b) within 30 days
     after you exercise your option.  Also, you should be aware that state and
     local income tax consequences may be quite different from the federal tax
     consequences.  For these reasons you should consult your tax advisor about
     possible tax consequences.

     The Company may require you to pay to the Company any amounts required by
     it to be withheld or paid under applicable tax requirements, including
     requirements resulting from the purchase of shares pursuant to this option.
     Any such payment shall be made in cash or by check at the time of exercise.

11.  LIMITED STOCK APPRECIATION RIGHTS. Because you are a director of the
     Company, subject to the "short swing" provisions of the Exchange Act of 
     1934, the Company has granted to you, in tandem with this option, limited 
     stock appreciation rights ("Limited Right") equal in number to the number 
     of shares covered by this option.  The terms and conditions governing the
     grant of this Limited Right are described in the Plan.

<PAGE>

12.  ACCEPTANCE WAIVER.  By accepting this option, you accept and agree to be 
     bound by each and all the terms and conditions of this agreement and of 
     the Plan. In case of any conflict between this agreement and the terms 
     of the Plan, the Plan shall control.  No waiver of any term or condition 
     of the agreement or the Plan shall be construed to be a waiver of any 
     other term or condition or to be a consent to any further waiver of the 
     same or any other term or condition.

13.  BINDING EFFECT.  Subject to the limitations of this agreement, this
     agreement shall be binding on, and inure to the benefit of, the executors, 
     administrators, heirs, legal representatives, successors and assigns of the
     parties hereto.



                                                  CETUS CORPORATION
                                                 
                                                   By:
                                                     ----------------------

ACCEPTED

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

Optionee