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                                                                    Exhibit 10.3


                                     MITOKOR
                    2000 OUTSIDE DIRECTORS STOCK OPTION PLAN


         1.  ESTABLISHMENT, PURPOSE AND TERM OF PLAN.

             1.1  ESTABLISHMENT. The MitoKor 2000 Outside Directors Stock Option
Plan (the "PLAN") is hereby established effective as of September 14, 2000 (the
"EFFECTIVE DATE").

             1.2  PURPOSE. The purpose of the Plan is to advance the interests
of the Participating Company Group and its stockholders by providing an
incentive to attract and retain highly qualified persons to serve as Outside
Directors of the Company and by creating additional incentive for Outside
Directors to promote the growth and profitability of the Participating Company
Group.

             1.3  TERM OF PLAN. The Plan shall continue in effect until the
earlier of its termination by the Board or the date on which all of the shares
of Stock available for issuance under the Plan have been issued and all
restrictions on such shares under the terms of the Plan and the agreements
evidencing Options granted under the Plan have lapsed.

         2.  DEFINITIONS AND CONSTRUCTION.

             2.1  DEFINITIONS. Whenever used herein, the following terms shall
have their respective meanings set forth below:

                  (a) "BOARD" means the Board of Directors of the Company. If
one or more Committees have been appointed by the Board to administer the Plan,
"Board" also means such Committee(s).

                  (b) "CODE" means the Internal Revenue Code of 1986, as
amended, and any applicable regulations promulgated thereunder.

                  (c) "COMMITTEE" means a committee of the Board duly appointed
to administer the Plan and having such powers as shall be specified by the
Board. Unless the powers of the Committee have been specifically limited, the
Committee shall have all of the powers of the Board granted herein, including,
without limitation, the power to amend or terminate the Plan at any time,
subject to the terms of the Plan and any applicable limitations imposed by law.

                  (d) "COMPANY" means MitoKor, Inc., a Delaware corporation, or
any successor corporation thereto.

                  (e) "CONSULTANT" means any person, including an advisor,
engaged by a Participating Company to render services other than as an Employee
or a Director.

                  (f) "DIRECTOR" means a member of the Board or the board of
directors of any other Participating Company.


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                  (g) "EMPLOYEE" means any person treated as an employee
(including an officer or a Director who is also treated as an employee) in the
records of a Participating Company; provided, however, that neither service as a
Director nor payment of a director's fee shall be sufficient to constitute
employment for purposes of the Plan.

                  (h) "EXCHANGE ACT" means the Securities Exchange Act of 1934,
as amended.

                  (i) "FAIR MARKET VALUE" means, as of any date, the value of a
share of Stock or other property as determined by the Board, in its sole
discretion, or by the Company, in its sole discretion, if such determination is
expressly allocated to the Company herein, subject to the following:

                      (i)   If, on such date, there is a public market for the
Stock, the Fair Market Value of a share of Stock shall be the closing sale price
of a share of Stock (or the mean of the closing bid and asked prices of a share
of Stock if the Stock is so quoted instead) as quoted on the Nasdaq National
Market, the Nasdaq Small-Cap Market or such other national or regional
securities exchange or market system constituting the primary market for the
Stock, as reported in the WALL STREET JOURNAL or such other source as the
Company deems reliable. If the relevant date does not fall on a day on which the
Stock has traded on such securities exchange or market system, the date on which
the Fair Market Value shall be established shall be the last day on which the
Stock was so traded prior to the relevant date, or such other appropriate day as
shall be determined by the Board, in its sole discretion.

                      (ii)  If, on such date, there is no public market for the
Stock, the Fair Market Value of a share of Stock shall be as determined by the
Board without regard to any restriction other than a restriction which, by its
terms, will never lapse.

                  (j) "OPTION" means a right to purchase Stock (subject to
adjustment as provided in Section 4.2) pursuant to the terms and conditions of
the Plan.

                  (k) "OPTIONEE" means a person who has been granted one or more
Options.

                  (l) "OPTION AGREEMENT" means a written agreement between the
Company and an Optionee setting forth the terms, conditions and restrictions of
the Option granted to the Optionee.

                  (m) "OUTSIDE DIRECTOR" means a Director of the Company who is
not an Employee of the Company.

                  (n) "PARENT CORPORATION" means any present or future "parent
corporation" of the Company, as defined in Section 424(e) of the Code.

                  (o) "PARTICIPATING COMPANY" means the Company or any Parent
Corporation or Subsidiary Corporation.


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                  (p) "PARTICIPATING COMPANY GROUP" means, at any point in time,
all corporations collectively which are then Participating Companies.

                  (q) "SERVICE" means the Optionee's service with the
Participating Company Group, whether in the capacity of an Employee, a Director
or a Consultant. The Optionee's Service shall not be deemed to have terminated
merely because of a change in the capacity in which the Optionee renders Service
to the Participating Company Group or a change in the Participating Company for
which the Optionee renders such Service, provided that there is no interruption
or termination of the Optionee's Service. The Optionee's Service shall be deemed
to have terminated either upon an actual termination of Service or upon the
corporation for which the Optionee performs Service ceasing to be a
Participating Company.

                  (r) "STOCK" means the common stock of the Company, as adjusted
from time to time in accordance with Section 4.2.

                  (s) "SUBSIDIARY CORPORATION" means any present or future
"subsidiary corporation" of the Company, as defined in Section 424(f) of the
Code.

             2.2  CONSTRUCTION. Captions and titles contained herein are for
convenience only and shall not affect the meaning or interpretation of any
provision of the Plan. Except when otherwise indicated by the context, the
singular shall include the plural, the plural shall include the singular, and
use of the term "or" shall include the conjunctive as well as the disjunctive.

         3.  ADMINISTRATION. The Plan shall be administered by the Board. All
questions of interpretation of the Plan or of any Option shall be determined by
the Board, and such determinations shall be final and binding upon all persons
having an interest in the Plan or such Option. Any officer of a Participating
Company shall have the authority to act on behalf of the Company with respect to
any matter, right, obligation, determination or election which is the
responsibility of or which is allocated to the Company herein, provided the
officer has apparent authority with respect to such matter, right, obligation,
determination or election.

         4.  SHARES SUBJECT TO PLAN.


             4.1  MAXIMUM NUMBER OF SHARES ISSUABLE. Subject to adjustment as
provided in Section 4.2, the maximum aggregate number of shares of Stock that
may be issued under the Plan (the "SHARE RESERVE") shall be Three Hundred Fifty
Thousand (350,000), cumulatively increased on January 1, 2003 and each January 1
thereafter by the lesser of (a) 50,000 shares of Stock, or (b) such lesser
number of shares of Stock as determined by the Board. The Share Reserve shall
consist of authorized but unissued shares or reacquired shares of Stock or any
combination thereof. If an outstanding Option for any reason expires or is
terminated or canceled or shares of Stock acquired, subject to repurchase, upon
the exercise of an Option are repurchased by the Company, the shares of Stock
allocable to the unexercised portion of such Option, or such repurchased shares
of Stock, shall again be available for issuance under the Plan.

             4.2  ADJUSTMENTS FOR CHANGES IN CAPITAL STRUCTURE. In the event of
any stock dividend, stock split, reverse stock split, recapitalization,
combination, reclassification or similar change in the capital structure of the
Company, appropriate adjustments shall be made in the


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number and class of shares subject to the Plan, to the "Initial Option" and
"Annual Option" (as defined in Section 6.1), and to any outstanding Options, and
in the exercise price of any outstanding Options. If a majority of the shares
which are of the same class as the shares that are subject to outstanding
Options are exchanged for, converted into, or otherwise become (whether or not
pursuant to an "Ownership Change Event" as defined in Section 8.1) shares of
another corporation (the "NEW Shares"), the Board may unilaterally amend the
outstanding Options to provide that such Options are exercisable for New Shares.
In the event of any such amendment, the number of shares subject to, and the
exercise price of, the outstanding Options shall be adjusted in a fair and
equitable manner as determined by the Board, in its sole discretion.
Notwithstanding the foregoing, any fractional share resulting from an adjustment
pursuant to this Section 4.2 shall be rounded down to the nearest whole number,
and in no event may the exercise price of any Option be decreased to an amount
less than the par value, if any, of the stock subject to the Option.

         5.  ELIGIBILITY AND TYPE OF OPTIONS.

             5.1  PERSONS ELIGIBLE FOR OPTIONS. An Option shall be granted only
to a person who, at the time of grant, is an Outside Director. Options may be
granted at the discretion of the Board or pursuant to the automatic grant
provisions of Section 6.1 below.

             5.2  OPTIONS AUTHORIZED. Options shall be nonstatutory stock
options; that is, options which are not treated as incentive stock options
within the meaning of Section 422(b) of the Code.

         6.  TERMS AND CONDITIONS OF OPTIONS. Options shall be evidenced by
Option Agreements specifying the number of shares of Stock covered thereby, in
such form as the Board shall from time to time establish. Option Agreements may
incorporate all or any of the terms of the Plan by reference and shall comply
with and be subject to the following terms and conditions:

             6.1  AUTOMATIC GRANT OF OPTIONS. Subject to execution by an Outside
Director of the appropriate Option Agreement, Options shall be granted
automatically and without further action of the Board, as follows:

                  (a) INITIAL OPTION. Each person who is (i) serving as an
Outside Director on the Effective Date, or (ii) first becomes an Outside
Director after the Effective Date shall be granted an Option to purchase Twenty
Thousand (20,000) shares of Stock on the Effective Date or the date such person
becomes an Outside Director, respectively (an "INITIAL OPTION"). Notwithstanding
anything herein to the contrary, an Initial Option shall not be granted to a
Director of the Company who previously did not qualify as an Outside Director
but subsequently becomes an Outside Director as a result of the termination of
his or her status as an Employee.

                  (b) ANNUAL OPTION. Each Outside Director (including any
Director who previously did not qualify as an Outside Director but who
subsequently becomes an Outside Director) shall be granted an Option to purchase
Five Thousand (5,000) shares of Stock on each of his or her "Anniversary Dates",
provided such person remains an Outside Director on such


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Anniversary Date (an "ANNUAL OPTION"). The Anniversary Date for an Outside
Director who was serving on the Board on the Effective Date shall be the date
which is twelve (12) months after the Effective Date and successive
anniversaries thereof. The Anniversary Date for a person who becomes an Outside
Director after the Effective Date shall be the date which is twelve (12) months
after such date and successive anniversaries thereof.

                  (c) RIGHT TO DECLINE OPTION. Notwithstanding the foregoing,
any person may elect not to receive an Option by delivering written notice of
such election to the Board no later than the day prior to the date such Option
would otherwise be granted. A person so declining an Option shall receive no
payment or other consideration in lieu of such declined Option. A person who has
declined an Option may revoke such election by delivering written notice of such
revocation to the Board no later than the day prior to the date such Option
would be granted pursuant to Section 6.1(a) or (b), as the case may be.

             6.2  EXERCISE PRICE. The exercise price per share of Stock subject
to an Option shall be the Fair Market Value of a share of Stock on the date the
Option is granted.

             6.3  EXERCISE PERIOD. Each Option shall terminate and cease to be
exercisable on the date ten (10) years after the date of grant of the Option
unless earlier terminated pursuant to the terms of the Plan or the Option
Agreement.

             6.4  RIGHT TO EXERCISE OPTIONS.

                  (a) INITIAL OPTIONS. Except as otherwise provided in the Plan
or in the Option Agreement, an Initial Option shall first become exercisable one
full month after the date on which the Initial Option was granted (the "INITIAL
OPTION VESTING DATE") and be exercisable on and after the Initial Option Vesting
Date and prior to the termination thereof in an amount equal to the number of
shares of Stock initially subject to the Initial Option multiplied by the Vested
Ratio as set forth below, less the number of shares previously acquired upon
exercise thereof. The Vested Ratio described in the preceding sentence shall be
determined as follows:

                                                                    Vested Ratio
                                                                    ------------

         On Initial Option Vesting Date                                 1/48

         Plus
         ----

         For each full month of the Optionee's continuous               1/48
         Service from the Initial Option Vesting Date until the
         Vested Ratio equals 1/1, an additional

The provisions of this Section 6.4(a) notwithstanding, the Initial Options for
Outside Directors who are Directors on the Effective Date shall vest immediately
as to fifty percent (50%) of the Stock subject to the Initial Option and the
remaining Stock subject to the Initial Option shall vest at the rate of 1/24 for
each full month of the Optionee's continuous service from the Effective Date.


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                   (b) ANNUAL OPTIONS. Except as otherwise provided in the Plan
or in the Option Agreement, an Annual Option shall first become exercisable one
full month after the date on which the Annual Option was granted (the "ANNUAL
OPTION VESTING DATE"); and be exercisable on and after the Annual Option Vesting
Date and prior to the termination thereof in an amount equal to the number of
shares of Stock initially subject to the Annual Option multiplied by the Vested
Ratio as set forth below, less the number of shares previously acquired upon
exercise thereof. The Vested Ratio described in the preceding sentence shall be
determined as follows:

                                                                    Vested Ratio
                                                                    ------------

         On Annual Option Vesting Date                                  1/12

         Plus
         ----

         For each full month of the Optionee's continuous               1/12
         Service from the Annual Option Vesting Date
         until the Vested Ratio equals 1/1, an additional

             6.5  PAYMENT OF EXERCISE PRICE.

                  (a) FORMS OF CONSIDERATION AUTHORIZED. Except as otherwise
provided below, payment of the exercise price for the number of shares of Stock
being purchased pursuant to any Option shall be made (i) in cash, by check, or
cash equivalent, (ii) by tender to the Company of shares of Stock owned by the
Optionee having a Fair Market Value not less than the exercise price, (iii) by
the assignment of the proceeds of a sale or loan with respect to some or all of
the shares being acquired upon the exercise of the Option (including, without
limitation, through an exercise complying with the provisions of Regulation T as
promulgated from time to time by the Board of Governors of the Federal Reserve
System) (a "CASHLESS EXERCISE"), or (iv) by any combination thereof.

                  (b) TENDER OF STOCK. Notwithstanding the foregoing, an Option
may not be exercised by tender to the Company of shares of Stock to the extent
such tender of Stock would constitute a violation of the provisions of any law,
regulation or agreement restricting the redemption of the Company's stock.
Unless otherwise provided by the Board, an Option may not be exercised by tender
to the Company of shares of Stock unless such shares either have been owned by
the Optionee for more than six (6) months or were not acquired, directly or
indirectly, from the Company.

                  (c) CASHLESS EXERCISE. The Company reserves, at any and all
times, the right, in the Company's sole and absolute discretion, to establish,
decline to approve or terminate any program or procedures for the exercise of
Options by means of a Cashless Exercise.

             6.6  TAX WITHHOLDING. The Company shall have the right, but not the
obligation, to deduct from the shares of Stock issuable upon the exercise of an
Option, or to accept from the Optionee the tender of, a number of whole shares
of Stock having a Fair Market Value equal to all or any part of the federal,
state, local and foreign taxes, if any, required by law


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to be withheld by the Participating Company Group with respect to such Option or
the shares acquired upon exercise thereof. Alternatively or in addition, in its
sole discretion, the Company shall have the right to require the Optionee to
make adequate provision for any such tax withholding obligations of the
Participating Company Group arising in connection with the Option or the shares
acquired upon exercise thereof. The Company shall have no obligation to deliver
shares of Stock until the Participating Company Group's tax withholding
obligations have been satisfied.

         7.  STANDARD FORM OF OPTION AGREEMENT.

             7.1  GENERAL. Each Option shall comply with and be subject to the
terms and conditions set forth in the appropriate form of Nonstatutory Stock
Option Agreement adopted by the Board concurrently with its adoption of the Plan
and as amended from time to time.

             7.2  AUTHORITY TO VARY TERMS. The Board shall have the authority
from time to time to vary the terms of any of the standard forms of Option
Agreement described in this Section 7 either in connection with the grant or
amendment of an individual Option or in connection with the authorization of a
new standard form or forms; provided, however, that the terms and conditions of
any such new, revised or amended standard form or forms of Option Agreement are
not inconsistent with the terms of the Plan.

         8.  CHANGE IN CONTROL.

             8.1  DEFINITIONS.

                  (a) An "OWNERSHIP CHANGE EVENT" shall be deemed to have
occurred if any of the following occurs with respect to the Company:

                      (i)   the direct or indirect sale or exchange in a single
or series of related transactions by the shareholders of the Company of more
than fifty percent (50%) of the voting stock of the Company;

                      (ii)  a merger or consolidation in which the Company is a
party;

                      (iii) the sale, exchange, or change in all or
substantially all of the assets of the Company; or

                      (iv)  a liquidation or dissolution of the Company.

                  (b) A "CHANGE IN CONTROL" shall mean an Ownership Change Event
or a series of related Ownership Change Events (collectively, the "TRANSACTION")
wherein the stockholders of the Company immediately before the Transaction do
not retain immediately after the Transaction, in substantially the same
proportions as their ownership of shares of the Company's voting stock
immediately before the Transaction, direct or indirect beneficial ownership of
more than fifty percent (50%) of the total combined voting power of the
outstanding voting stock of the Company or the corporation or corporations to
which the assets of the Company were transferred (the "TRANSFEREE
CORPORATION(S)"), as the case may be. For purposes of the preceding sentence,
indirect beneficial ownership shall include, without


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limitation, an interest resulting from ownership of the voting stock of one or
more corporations which, as a result of the Transaction, own the Company or the
Transferee Corporation(s), as the case may be, either directly or through one or
more subsidiary corporations. The Board shall have the right to determine
whether multiple sales or exchanges of the voting stock of the Company or
multiple Ownership Change Events are related, and its determination shall be
final, binding and conclusive.

            8.2  EFFECT OF CHANGE IN CONTROL ON OPTIONS. In the event of a
Change in Control, any unexercisable or unvested portion of the outstanding
Options shall be immediately exercisable and vested in full as of the date ten
(10) days prior to the date of the Change in Control. The exercise or vesting of
any Option that was permissible solely by reason of this Section 8.2 shall be
conditioned upon the consummation of the Change in Control. In addition, the
surviving, continuing, successor, or purchasing corporation or parent
corporation thereof, as the case may be (the "ACQUIRING CORPORATION"), may
either assume the Company's rights and obligations under outstanding Options or
substitute for outstanding Options substantially equivalent options for the
Acquiring Corporation's stock. For purposes of this Section 8.2, an Option shall
be deemed assumed if, following the Change in Control, the Option confers the
right to purchase in accordance with its terms and conditions, for each share of
Stock subject to the Option immediately prior to the Change in Control, the
consideration (whether stock, cash or other securities or property) to which a
holder of a share of Stock on the effective date of the Change in Control was
entitled. Any Options which are neither assumed or substituted for by the
Acquiring Corporation in connection with the Change in Control nor exercised as
of the date of the Change in Control shall terminate and cease to be outstanding
effective as of the date of the Change in Control. Notwithstanding the
foregoing, shares acquired upon exercise of an Option prior to the Change in
Control and any consideration received pursuant to the Change in Control with
respect to such shares shall continue to be subject to all applicable provisions
of the Option Agreement evidencing such Option except as otherwise provided in
such Option Agreement. Furthermore, notwithstanding the foregoing, if the
corporation the stock of which is subject to the outstanding Options immediately
prior to an Ownership Change Event described in Section 8.1(a)(i) constituting a
Change in Control is the surviving or continuing corporation and immediately
after such Ownership Change Event less than fifty percent (50%) of the total
combined voting power of its voting stock is held by another corporation or by
other corporations that are members of an affiliated group within the meaning of
Section 1504(a) of the Code without regard to the provisions of Section 1504(b)
of the Code, the outstanding Options shall not terminate.

         9.  NONTRANSFERABILITY OF OPTIONS. During the lifetime of the Optionee,
an Option shall be exercisable only by the Optionee or the Optionee's guardian
or legal representative. No Option shall be assignable or transferable by the
Optionee, except by will or by the laws of descent and distribution.

        10.  INDEMNIFICATION. In addition to such other rights of
indemnification as they may have as members of the Board or officers or
employees of the Participating Company Group, members of the Board and any
officers or employees of the Participating Company Group to whom authority to
act for the Board is delegated shall be indemnified by the Company against all
reasonable expenses, including attorneys' fees, actually and necessarily
incurred in connection with the defense of any action, suit or proceeding, or in
connection with any appeal therein, to


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which they or any of them may be a party by reason of any action taken or
failure to act under or in connection with the Plan, or any right granted
hereunder, and against all amounts paid by them in settlement thereof (provided
such settlement is approved by independent legal counsel selected by the
Company) or paid by them in satisfaction of a judgment in any such action, suit
or proceeding, except in relation to matters as to which it shall be adjudged in
such action, suit or proceeding that such person is liable for gross negligence,
bad faith or intentional misconduct in duties; provided, however, that within
sixty (60) days after the institution of such action, suit or proceeding, such
person shall offer to the Company, in writing, the opportunity at its own
expense to handle and defend the same.

        11.  TERMINATION OR AMENDMENT OF PLAN. The Board may terminate or amend
the Plan at any time. However, subject to changes in applicable law, regulations
or rules that would permit otherwise, without the approval of the Company's
shareholders, there shall be (a) no increase in the total number of shares of
Stock that may be issued under the Plan (except by operation of the provisions
of Section 4.2), and (b) no other amendment of the Plan that would require
approval of the Company's shareholders under any applicable law, regulation or
rule. In any event, no termination or amendment of the Plan may adversely affect
any then outstanding Option, or any unexercised portion thereof, without the
consent of the Optionee, unless such termination or amendment is necessary to
comply with any applicable law, regulation or rule.


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                                  PLAN HISTORY



September 14, 2000     Board of Directors of MitoKor, a California corporation
                       ("MitoKor California") adopts Plan, with an initial
                       reserve of 200,000 shares.

October 18, 2000       Shareholders of MitoKor California approve Plan, with
                       an initial reserve of 200,000 shares.

February 1, 2001       Board of MitoKor California amends the definition of
                       "Outside Director" to include directors who are
                       representatives or nominees of a shareholder.

May 3, 2001            Board of MitoKor California approves a share reserve
                       increase of 50,000 shares, for a total reserve of
                       250,000 shares.

June 5, 2001           Shareholders of MitoKor California approve (i) amendment
                       of the definition of "Outside Director" to include
                       directors who are representatives or nominees of a
                       shareholder and (ii) an increase to the share reserve by
                       50,000 shares, for a total of 250,000 shares.

April 17, 2002         Board of MitoKor California approves a share reserve
                       increase of 100,000 shares, for a total reserve of
                       350,000 shares, increased on January 1, 2003 and each
                       January 1 thereafter by 50,000 shares (or such lesser
                       number of shares determined by the Board).

_______, 2002          Shareholders of MitoKor California approve increase to
                       the share reserve by 100,000 shares, for a total of
                       350,000 shares, increased on January 1, 2003 and each
                       January 1 thereafter by 50,000 shares (or such lesser
                       number of shares determined by the Board).

_______, 2002          Effective date of Delaware reincorporation of MitoKor
                       California.



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                                     MITOKOR
                             STOCK OPTION AGREEMENT
                   (2000 OUTSIDE DIRECTORS STOCK OPTION PLAN)

         MitoKor, Inc. has granted to the individual (the "OPTIONEE") named in
the NOTICE OF GRANT OF STOCK OPTIONS (the "NOTICE") to which this Stock Option
Agreement (the "OPTION AGREEMENT") is attached an option (the "OPTION") to
purchase certain shares of Stock upon the terms and conditions set forth in the
Notice and this Option Agreement. The Option has been granted pursuant to and
shall in all respects be subject to the terms and conditions of the MitoKor,
Inc. 2000 Outside Directors Stock Option Plan (the "PLAN"), as amended to the
Date of Option Grant, the provisions of which are incorporated herein by
reference. By signing the Notice, the Optionee: (a) represents that the Optionee
has read and is familiar with the terms and conditions of the Notice, the Plan
and this Option Agreement, including the Effect of Termination of Service set
forth in Section 7, (b) accepts the Option subject to all of the terms and
conditions of the Notice, the Plan and this Option Agreement, (c) agrees to
accept as binding, conclusive and final all decisions or interpretations of the
Board upon any questions arising under the Notice, the Plan or this Option
Agreement, and (d) acknowledges receipt of a copy of the Notice, the Plan and
this Option Agreement.

         1.  DEFINITIONS AND CONSTRUCTION.

             1.1  DEFINITIONS. Unless otherwise defined herein, capitalized
terms shall have the meanings assigned to such terms in the Plan. Whenever used
herein, the following terms shall have their respective meanings set forth
below:

                  (a) "DATE OF OPTION GRANT" means the effective date of grant
of the Option as set forth in the Notice.

                  (b) "NUMBER OF OPTION SHARES" means the total number of shares
of Stock subject to the Option as set forth in the Notice and as adjusted from
time to time pursuant to Section 9.

                  (c) "EXCHANGE ACT" means the Securities Exchange Act of 1934,
as amended.

                  (d) "EXERCISE PRICE" means the purchase price per share of
Stock as set forth in the Notice and as adjusted from time to time pursuant to
Section 9.

                  (e) "OPTION EXPIRATION DATE" means the date ten (10) years
after the Date of Option Grant.

                  (f) "COMPANY" means MitoKor, Inc., a Delaware corporation, or
any successor corporation thereto.

                  (g) "DISABILITY" means the inability of the Optionee, in the
opinion of a qualified physician acceptable to the Company, to perform the major
duties of the Optionee's


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position with the Participating Company Group because of the sickness or injury
of the Optionee.

                  (h) "SECURITIES ACT" means the Securities Act of 1933, as
amended.

                  (i) "SERVICE" means the Optionee's employment or service with
the Participating Company Group, whether in the capacity of an Employee, a
Director or a Consultant. The Optionee's Service shall not be deemed to have
terminated merely because of a change in the capacity in which the Optionee
renders Service to the Participating Company Group or a change in the
Participating Company for which the Optionee renders such Service, provided that
there is no interruption or termination of the Optionee's Service. The
Optionee's Service shall be deemed to have terminated either upon an actual
termination of Service or upon the corporation for which the Optionee performs
Service ceasing to be a Participating Company. Subject to the foregoing, the
Company, in its sole discretion, shall determine whether the Optionee's Service
has terminated and the effective date of such termination.

                  (j) "VESTED SHARES" means, except as otherwise provided
herein, on any relevant date, that portion of the Number of Option Shares which
has vested in accordance with vesting schedule set forth in the Notice. Provided
that the Optionee's Service has not terminated prior to the relevant date, an
initial installment of shares will become Vested Shares on the initial "Full
Vest" date set forth in the Notice, and thereafter the remaining shares will
become Vested Shares in substantially equal installments at the periodic rate
set forth in the Notice, with the last such installment vesting on the last
"Full Vest" date set forth in the Notice.

             1.2  CONSTRUCTION. Captions and titles contained herein are for
convenience only and shall not affect the meaning or interpretation of any
provision of this Option Agreement. Except when otherwise indicated by the
context, the singular shall include the plural, the plural shall include the
singular, and the term "or" shall include the conjunctive as well as the
disjunctive.

         2.  TAX STATUS OF OPTION. This Option is intended to be a Nonstatutory
Stock Option and shall not be treated as an incentive stock option within the
meaning of Section 422(b) of the Code.

         3.  ADMINISTRATION. All questions of interpretation concerning this
Option Agreement shall be determined by the Board, including any duly appointed
Committee of the Board. All determinations by the Board shall be final and
binding upon all persons having an interest in the Option. Any officer of a
Participating Company shall have the authority to act on behalf of the Company
with respect to any matter, right, obligation, or election which is the
responsibility of or which is allocated to the Company herein, provided the
officer has apparent authority with respect to such matter, right, obligation,
or election.

         4.  EXERCISE OF THE OPTION.

             4.1  RIGHT TO EXERCISE. Except as otherwise provided herein, the
Option shall be exercisable on and after the Date of Option Grant and prior to
the termination of the Option (as provided in Section 6) in an amount not to
exceed the number of Vested Shares, less the


                                       2

<Page>


number of shares previously acquired upon exercise of the Option. In no event
shall the Option be exercisable for more shares than the Number of Option
Shares.

             4.2  METHOD OF EXERCISE. Exercise of the Option shall be by written
notice to the Company which must state the election to exercise the Option, the
number of whole shares of Stock for which the Option is being exercised and such
other representations and agreements as to the Optionee's investment intent with
respect to such shares as may be required pursuant to the provisions of this
Option Agreement. The written notice must be signed by the Optionee and must be
delivered in person, by certified or registered mail, return receipt requested,
by confirmed facsimile transmission, or by such other means as the Company may
permit, to the Chief Financial Officer of the Company, or other authorized
representative of the Participating Company Group, prior to the termination of
the Option as set forth in Section 6, accompanied by full payment of the
aggregate Exercise Price for the number of shares of Stock being purchased. The
Option shall be deemed to be exercised upon receipt by the Company of such
written notice and the aggregate Exercise Price.

             4.3  PAYMENT OF EXERCISE PRICE.

                  (a) FORMS OF CONSIDERATION AUTHORIZED. Except as otherwise
provided below, payment of the aggregate Exercise Price for the number of shares
of Stock for which the Option is being exercised shall be made (i) in cash, by
check, or cash equivalent, (ii) by tender to the Company of whole shares of
Stock owned by the Optionee having a Fair Market Value (as determined by the
Company without regard to any restrictions on transferability applicable to such
stock by reason of federal or state securities laws or agreements with an
underwriter for the Company) not less than the aggregate Exercise Price, (iii)
by means of a Cashless Exercise, as defined in Section 4.3(c), or (iv) by any
combination of the foregoing.

                  (b) TENDER OF STOCK. Notwithstanding the foregoing, the Option
may not be exercised by tender to the Company of shares of Stock to the extent
such tender of Stock would constitute a violation of the provisions of any law,
regulation or agreement restricting the redemption of the Company's stock. The
Option may not be exercised by tender to the Company of shares of Stock unless
such shares either have been owned by the Optionee for more than six (6) months
or were not acquired, directly or indirectly, from the Company.

                  (c) CASHLESS EXERCISE. A "CASHLESS EXERCISE" means the
assignment in a form acceptable to the Company of the proceeds of a sale or loan
with respect to some or all of the shares of Stock acquired upon the exercise of
the Option pursuant to a program or procedure approved by the Company
(including, without limitation, through an exercise complying with the
provisions of Regulation T as promulgated from time to time by the Board of
Governors of the Federal Reserve System). The Company reserves, at any and all
times, the right, in the Company's sole and absolute discretion, to decline to
approve or terminate any such program or procedure.

             4.4  TAX WITHHOLDING. At the time the Option is exercised, in whole
or in part, or at any time thereafter as requested by the Company, the Optionee
hereby authorizes withholding from payroll and any other amounts payable to the
Optionee, and otherwise agrees to make adequate provision for (including by
means of a Cashless Exercise to the extent


                                       3

<Page>


permitted by the Company), any sums required to satisfy the federal, state,
local and foreign tax withholding obligations of the Participating Company
Group, if any, which arise in connection with the Option, including, without
limitation, obligations arising upon (i) the exercise, in whole or in part, of
the Option, (ii) the transfer, in whole or in part, of any shares acquired upon
exercise of the Option, (iii) the operation of any law or regulation providing
for the imputation of interest, or (iv) the lapsing of any restriction with
respect to any shares acquired upon exercise of the Option. The Optionee is
cautioned that the Option is not exercisable unless the tax withholding
obligations of the Participating Company Group are satisfied. Accordingly, the
Optionee may not be able to exercise the Option when desired even though the
Option is vested, and the Company shall have no obligation to issue a
certificate for such shares.

             4.5  CERTIFICATE REGISTRATION. Except in the event the Exercise
Price is paid by means of a Cashless Exercise, the certificate for the shares as
to which the Option is exercised shall be registered in the name of the
Optionee, or, if applicable, in the names of the heirs of the Optionee.

             4.6  RESTRICTIONS ON GRANT OF THE OPTION AND ISSUANCE OF SHARES.
The grant of the Option and the issuance of shares of Stock upon exercise of the
Option shall be subject to compliance with all applicable requirements of
federal, state or foreign law with respect to such securities. The Option may
not be exercised if the issuance of shares of Stock upon exercise would
constitute a violation of any applicable federal, state or foreign securities
laws or other law or regulations or the requirements of any stock exchange or
market system upon which the Stock may then be listed. In addition, the Option
may not be exercised unless (i) a registration statement under the Securities
Act shall at the time of exercise of the Option be in effect with respect to the
shares issuable upon exercise of the Option or (ii) in the opinion of legal
counsel to the Company, the shares issuable upon exercise of the Option may be
issued in accordance with the terms of an applicable exemption from the
registration requirements of the Securities Act. THE OPTIONEE IS CAUTIONED THAT
THE OPTION MAY NOT BE EXERCISED UNLESS THE FOREGOING CONDITIONS ARE SATISFIED.
ACCORDINGLY, THE OPTIONEE MAY NOT BE ABLE TO EXERCISE THE OPTION WHEN DESIRED
EVEN THOUGH THE OPTION IS VESTED. The inability of the Company to obtain from
any regulatory body having jurisdiction the authority, if any, deemed by the
Company's legal counsel to be necessary to the lawful issuance and sale of any
shares subject to the Option shall relieve the Company of any liability in
respect of the failure to issue or sell such shares as to which such requisite
authority shall not have been obtained. As a condition to the exercise of the
Option, the Company may require the Optionee to satisfy any qualifications that
may be necessary or appropriate, to evidence compliance with any applicable law
or regulation and to make any representation or warranty with respect thereto as
may be requested by the Company.

             4.7  FRACTIONAL SHARES. The Company shall not be required to issue
fractional shares upon the exercise of the Option.

         5.  TRANSFERABILITY OF THE OPTION. The Option may be exercised during
the lifetime of the Optionee only by the Optionee or the Optionee's guardian or
legal representative and may not be assigned or transferred in any manner except
by will or by the laws of descent and distribution. Following the death of the
Optionee, the Option, to the extent provided in Section 7, may be exercised by
the Optionee's legal representative or by any person empowered


                                       4
<Page>


to do so under the deceased Optionee's will or under the then applicable laws of
descent and distribution.

         6.  TERMINATION OF THE OPTION. The Option shall terminate and may no
longer be exercised on the first to occur of (a) the Option Expiration Date, (b)
the last date for exercising the Option following termination of the Optionee's
Service as described in Section 7, or (c) a Change in Control to the extent
provided in Section 8.

         7.  EFFECT OF TERMINATION OF SERVICE.

             7.1  OPTION EXERCISABILITY.

                  (a) DISABILITY. If the Optionee's Service with the
Participating Company Group is terminated because of the Disability of the
Optionee, the Option, to the extent unexercised and exercisable on the date on
which the Optionee's Service terminated, may be exercised by the Optionee (or
the Optionee's guardian or legal representative) at any time prior to the
expiration of twelve (12) months after the date on which the Optionee's Service
terminated, but in any event no later than the Option Expiration Date.

                  (b) DEATH. If the Optionee's Service with the Participating
Company Group is terminated because of the death of the Optionee, the Option, to
the extent unexercised and exercisable on the date on which the Optionee's
Service terminated, may be exercised by the Optionee (or the Optionee's legal
representative, or other person who acquired the right to exercise the Option by
reason of the Optionee's death) at any time prior to the expiration of twelve
(12) months after the date on which the Optionee's Service terminated, but in
any event no later than the Option Expiration Date. The Optionee's Service shall
be deemed to have terminated on account of death if the Optionee dies within
ninety (90) days after the Optionee's termination of Service.

                  (c) OTHER TERMINATION OF SERVICE. If the Optionee's Service
with the Participating Company Group terminates for any reason, except
Disability or death, the Option, to the extent unexercised and exercisable by
the Optionee on the date on which the Optionee's Service terminated, may be
exercised by the Optionee within six (6) months (or such other longer period of
time as determined by the Board, in its sole discretion) after the date on which
the Optionee's Service terminated, but in any event no later than the Option
Expiration Date.

             7.2  EXTENSION IF EXERCISE PREVENTED BY LAW. Notwithstanding the
foregoing, if the exercise of the Option within the applicable time periods set
forth in Section 7.1 is prevented by the provisions of Section 4.6, the Option
shall remain exercisable until three (3) months after the date the Optionee is
notified by the Company that the Option is exercisable, but in any event no
later than the Option Expiration Date.

             7.3  EXTENSION IF OPTIONEE SUBJECT TO SECTION 16(B).
Notwithstanding the foregoing, if a sale within the applicable time periods set
forth in Section 7.1 of shares acquired upon the exercise of the Option would
subject the Optionee to suit under Section 16(b) of the Exchange Act, the Option
shall remain exercisable until the earliest to occur of (i) the tenth (10th) day
following the date on which a sale of such shares by the Optionee would no
longer be


                                       5

<Page>


subject to such suit, (ii) the one hundred and ninetieth (190th) day after the
Optionee's termination of Service, or (iii) the Option Expiration Date.

             7.4  LEAVE OF ABSENCE. For purposes of Section 7.1, the Optionee's
Service with the Participating Company Group shall not be deemed to terminate if
the Optionee takes any military leave, sick leave, or other bona fide leave of
absence approved by the Company of ninety (90) days or less. In the event of a
leave of absence in excess of ninety (90) days, the Optionee's Service shall be
deemed to terminate on the ninety-first (91st) day of such leave unless the
Optionee's right to reemployment with the Participating Company Group remains
guaranteed by statute or contract. Notwithstanding the foregoing, unless
otherwise designated by the Company (or required by law), a leave of absence
shall not be treated as Service for purposes of determining the Optionee's
Vested Ratio.

         8.  CHANGE IN CONTROL.

             8.1  DEFINITIONS.

                  (a) An "OWNERSHIP CHANGE EVENT" shall be deemed to have
occurred if any of the following occurs with respect to the Company:

                      (i)   the direct or indirect sale or exchange in a single
or series of related transactions by the stockholders of the Company of more
than fifty percent (50%) of the voting stock of the Company;

                      (ii)  a merger or consolidation in which the Company is a
party; or

                      (iii) the sale, exchange, or transfer of all or
substantially all of the assets of the Company; or

                      (iv)  a liquidation or dissolution of the Company.

                  (b) A "CHANGE IN CONTROL" shall mean an Ownership Change Event
or a series of related Ownership Change Events (collectively, the "TRANSACTION")
wherein the stockholders of the Company immediately before the Transaction do
not retain immediately after the Transaction, in substantially the same
proportions as their ownership of shares of the Company's voting stock
immediately before the Transaction, direct or indirect beneficial ownership of
more than fifty percent (50%) of the total combined voting power of the
outstanding voting stock of the Company or the corporation or corporations to
which the assets of the Company were transferred (the "TRANSFEREE
CORPORATION(S)"), as the case may be. For purposes of the preceding sentence,
indirect beneficial ownership shall include, without limitation, an interest
resulting from ownership of the voting stock of one or more corporations which,
as a result of the Transaction, own the Company or the Transferee
Corporation(s), as the case may be, either directly or through one or more
subsidiary corporations. The Board shall have the right to determine whether
multiple sales or exchanges of the voting stock of the Company or multiple
Ownership Change Events are related, and its determination shall be final,
binding and conclusive.


                                       6
<Page>


             8.2  EFFECT OF CHANGE IN CONTROL ON OPTION. In the event of a
Change in Control, any unexercised portion of the Option shall be immediately
exercisable and vested in full as of the date ten (10) days prior to the date of
the Change in Control. Any exercise or vesting of any Option that was
permissible solely by reason of this Section 8.2 shall be conditioned upon the
consummation of the Change in Control. In addition, the surviving, continuing,
successor, or purchasing corporation or parent corporation thereof, as the case
may be (the "ACQUIRING CORPORATION"), may either assume the Company's rights and
obligations under outstanding Options or substitute for outstanding Options
substantially equivalent options for the Acquiring Corporation's stock. For
purposes of this Section 8.2, an Option shall be deemed assumed if, following
the Change in Control, the Option confers the right to purchase in accordance
with its terms and conditions, for each share of Stock subject to the Option
immediately prior to the Change in Control, the consideration (whether stock,
cash or other securities or property) to which a holder of a share of Stock on
the effective date of the Change in Control was entitled. Any Options which are
neither assumed or substituted for by the Acquiring Corporation in connection
with the Change in Control nor exercised as of the date of the Change in Control
shall terminate and cease to be outstanding effective as of the date of the
Change in Control. Notwithstanding the foregoing, shares acquired upon exercise
of an Option prior to the Change in Control and any consideration received
pursuant to the Change in Control with respect to such shares shall continue to
be subject to all applicable provisions of the Option Agreement evidencing such
Option except as otherwise provided in such Option Agreement. Furthermore,
notwithstanding the foregoing, if the corporation the stock of which is subject
to the outstanding Options immediately prior to an Ownership Change Event
described in Section 8.1(a)(i) constituting a Change in Control is the surviving
or continuing corporation and immediately after such Ownership Change Event less
than fifty percent (50%) of the total combined voting power of its voting stock
is held by another corporation or by other corporations that are members of an
affiliated group within the meaning of Section 1504(a) of the Code without
regard to the provisions of Section 1504(b) of the Code, the outstanding Options
shall not terminate.

         9.  ADJUSTMENTS FOR CHANGES IN CAPITAL STRUCTURE. In the event of any
stock dividend, stock split, reverse stock split, recapitalization, combination,
reclassification, or similar change in the capital structure of the Company,
appropriate adjustments shall be made in the number, Exercise Price and class of
shares of stock subject to the Option. If a majority of the shares which are of
the same class as the shares that are subject to the Option are exchanged for,
converted into, or otherwise become (whether or not pursuant to an Ownership
Change Event) shares of another corporation (the "NEW SHARES"), the Board may
unilaterally amend the Option to provide that the Option is exercisable for New
Shares. In the event of any such amendment, the Number of Option Shares and the
Exercise Price shall be adjusted in a fair and equitable manner, as determined
by the Board, in its sole discretion. Notwithstanding the foregoing, any
fractional share resulting from an adjustment pursuant to this Section 9 shall
be rounded up or down to the nearest whole number, as determined by the Board,
and in no event may the Exercise Price be decreased to an amount less than the
par value, if any, of the stock subject to the Option. The adjustments
determined by the Board pursuant to this Section 9 shall be final, binding and
conclusive.

        10.  RIGHTS AS A STOCKHOLDER OR SERVICE PROVIDER. The Optionee shall
have no rights as a stockholder with respect to any shares covered by the Option
until the date of the issuance of


                                       7

<Page>


a certificate for the shares for which the Option has been exercised (as
evidenced by the appropriate entry on the books of the Company or of a duly
authorized transfer agent of the Company). No adjustment shall be made for
dividends, distributions or other rights for which the record date is prior to
the date such certificate is issued, except as provided in Section 9. Nothing in
this Option Agreement shall confer upon the Optionee any right to continue in
the Service of a Participating Company or interfere in any way with any right of
the Participating Company Group to terminate the Optionee's Service at any
acquiring the Securities solely for the Optionee's own account for investment
and not with a view to or for sale in connection with any distribution of the
Securities or any portion thereof and not with any present intention of selling,
offering to sell or otherwise disposing of or distributing the Securities or any
portion thereof in any transaction other than a transaction exempt from
registration under the Securities Act. The Optionee further represents that the
entire legal and beneficial interest of the Securities is being acquired, and
will be held, for the account of the Optionee only and neither in whole nor in
part for any other person

        11.  LEGENDS. The Company may at any time place legends any applicable
federal, state or foreign securities law restrictions on all certificates
representing shares of stock subject to the provisions of this Option Agreement.
The Optionee shall, at the request of the Company, promptly present to the
Company any and all certificates representing shares acquired pursuant to the
Option in the possession of the Optionee in order to carry out the provisions of
this Section.

        12.  BINDING EFFECT. Subject to the restrictions on transfer set forth
herein, this Option Agreement shall inure to the benefit of and be binding upon
the parties hereto and their respective heirs, executors, administrators,
successors and assigns.

        13.  TERMINATION OR AMENDMENT. The Board may terminate or amend the Plan
or the Option at any time; provided, however, that except as provided in Section
8.2 in connection with a Change in Control, no such termination or amendment may
adversely affect the Option or any unexercised portion hereof without the
consent of the Optionee unless such termination or amendment is necessary to
comply with any applicable law or government regulation. No amendment or
addition to this Option Agreement shall be effective unless in writing.

        14.  INTEGRATED AGREEMENT. The Notice, this Option Agreement and the
Plan constitute the entire understanding and agreement of the Optionee and the
Participating Company Group with respect to the subject matter contained herein
and therein and there are no agreements, understandings, restrictions,
representations, or warranties among the Optionee and the Participating Company
Group with respect to such subject matter other than those as set forth or
provided for herein or therein. To the extent contemplated herein or therein,
the provisions of the Notice and this Option Agreement shall survive any
exercise of the Option and shall remain in full force and effect.

        15.  APPLICABLE LAW. This Option Agreement shall be governed by the laws
of the State of California as such laws are applied to agreements between
California residents entered into and to be performed entirely within the State
of California.


                                        8


<Page>

                                           Optionee:
                                                    --------------------

                                                               Date:
                                                                    ------------


                          STOCK OPTION EXERCISE NOTICE
                               (REGISTERED SHARES)



MitoKor, Inc.
Attention: Chief Financial Officer
11494 Sorrento Valley Road
San Diego, CA  92121

Ladies and Gentlemen:

         1.  OPTION. I was granted a nonstatutory stock option (the "OPTION") to
purchase shares of the common stock (the "SHARES") of MitoKor, Inc. (the
"COMPANY") pursuant to the Company's 2000 Outside Directors Stock Option Plan
(the "PLAN"), my Notice of Grant of Stock Options (the "NOTICE") and my Stock
Option Agreement (the "OPTION AGREEMENT") as follows:

             Grant Number:
                                                                      ----------

             Date of Option Grant:
                                                                      ----------

             Number of Option Shares:
                                                                      ----------

             Exercise Price per Share:                                $
                                                                      ----------

         2.  EXERCISE OF OPTION. I hereby elect to exercise the Option to
purchase the following number of Shares:

             Total Shares Purchased:
                                                                      ----------

             Total Exercise Price (Total Shares  X  Price per Share)  $
                                                                      ----------

         3.  PAYMENTS. I enclose payment in full of the total exercise price for
the Shares in the following form(s), as authorized by my Option Agreement:

             (TM)  Cash:                                              $
                                                                      ----------

             (TM)  Check:                                             $
                                                                      ----------

             (TM)  Tender of Company Stock:           Contact Plan Administrator

             (TM)  Cashless exercise                  Contact Plan Administrator


                                       1

<Page>

         4.  OPTIONEE INFORMATION.


             My address is:
                           -------------------------------------

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


             My Social Security Number is:
                                          ----------------------

         5.  BINDING EFFECT. I agree that the Shares are being acquired in
accordance with and subject to the terms, provisions and conditions of the
Option Agreement, to all of which I hereby expressly assent. This Agreement
shall inure to the benefit of and be binding upon the my heirs, executors,
administrators, successors and assigns.

         I understand that I am purchasing the Shares pursuant to the terms of
the Plan, the Notice and my Option Agreement, copies of which I have received
and carefully read and understand.

                                       Very truly yours,



                                       -------------------------
                                       (Signature)


Receipt of the above is hereby acknowledged.

MITOKOR, INC.

By:
   -------------------------------------------

Title:
      ----------------------------------------

Dated:
      ----------------------------------------


                                       2