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                                                               EXHIBIT 10.16

                              KIVA GENETICS, INC.

                              EMPLOYMENT AGREEMENT

     This Employment Agreement (the "AGREEMENT") is dated as of March 9,
1999, by and between Hugh Y. Rienhoff, Jr. ("Employee") and Kiva Genetics,
Inc., a Delaware corporation (the "COMPANY"), and is intended to supersede
and replace the prior Employment Agreement dated November 1, 1998, which
prior Employment Agreement is hereby terminated.

     1.   TERM OF AGREEMENT. This Agreement shall commence on the date
hereof and continue until properly terminated in accordance with Section 5.

     2.   DUTIES.

          (a)  POSITION. Employee shall be employed as Chairman and Chief
Executive Officer and will report to the Company's Board of Directors.

          (b)  OBLIGATIONS TO THE COMPANY. Employee agrees to the best of his
ability and experience that he will at all times loyally and conscientiously
perform all of the duties and obligations required of and from Employee
pursuant to the express and implicit terms hereof, and to the reasonable
satisfaction of the Company. During the term of Employee's employment
relationship with the Company, and except as otherwise specified herein,
Employee further agrees that he will devote all of his business time and
attention to the business of the Company. During the term of his employment
and the Severance Period (if any) Employee will not directly or indirectly
engage or participate in any business that is competitive in any manner with
the business of the Company. Employee will comply with and be bound by the
Company's operating policies, procedures and practices from time to time in
effect during the term of Employee's employment.

     3.   AT-WILL EMPLOYMENT. The Company and Employee acknowledge that
Employee's employment is and shall continue to be at-will, as defined under
applicable law, and that Employee's employment with the Company may be
terminated by either party at any time for any or no reason, with or without
Cause. If Employee's employment terminates for any or no reason, Employee
shall not be entitled to any payments, benefits, damages, award or
compensation other than as provided in this Agreement.

     4.   COMPENSATION. For the duties and services to be performed by
Employee hereunder, the Company shall pay Employee, and Employee agrees to
accept, the salary, stock options, bonuses and other benefits described below
in this Section 4.

          (a)  SALARY. Employee shall receive a monthly salary of $20,833.33,
which is equivalent to $250,000 on an annualized basis. Employee's monthly
salary will be payable in two (2) equal biweekly installments pursuant to the
Company's normal payroll practices. The salary shall be reviewed at
reasonable intervals by the Board, or its Compensation Committee, and any
increase will be effective as of the date determined appropriate by the
Board, or its Compensation Committee.

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         (b)  BONUSES. Employee will be eligible to receive an annual cash
bonus (the "ANNUAL BONUS"), the exact amount to be determined based upon
performance against milestones established annually by the Board or its
Compensation Committee. In addition to the Annual Bonus, Employee will
participate in and, to the extent earned or otherwise payable thereunder,
receive periodic incentive cash bonuses pursuant to the incentive bonus
programs currently maintained or hereafter established by the Company for its
executives generally or pursuant to one or more substantially equivalent
programs. Employee's entitlement to incentive bonuses is discretionary and
will be determined by the Board or its Compensation Committee in good faith
based upon the extent to which Employee's individual performance objectives
and the Company's financial and nonfinancial objectives were achieved during
the applicable bonus period.

         (c)   MOVING EXPENSES. The Company will pay the reasonable moving
and storage expenses of Employee in relocating to the San Francisco Bay Area.

         (d)   HOUSING EXPENSES. The Company will provide Employee with a
housing loan of $100,000 in the form of a promissory note (the "Note")
secured by all shares of Common Stock held by Employee and forgivable over a
four year period at a rate of 1/4 of the loan each year based upon continued
employment. The Note shall be due and payable (to the extent not forgiven)
upon termination of employment with Cause, upon Voluntary Termination
pursuant to Section 5(a)(iii) below, or upon the sale of such Common Stock
held by Employee. The Note and any augmented amounts to the Note, as set
forth below, shall be forgiven upon the Involuntary Termination of Employee
pursuant to Section 5(b)(ii) below. In addition, Employee will be entitled to
receive up to $48,000 in reimbursement for Employee's out of pocket expenses
associated with interim housing costs. Any unused portion of such $48,000
amount may be augmented to the Note on the same terms as pertain to the Note.

         (e)   ADDITIONAL BENEFITS. Employee will have the ability to
participate in the Company's employee benefit plans of general application,
including, without limitation, those plans covering medical and disability
insurance in accordance with the rules established for individual
participation in any such plan and under applicable law. Employee will be
eligible for vacation and sick leave in accordance with the policies in
effect at the Company during the term of this Agreement and will receive such
other benefits as the Company generally provides to its other employees of
comparable position and experience.

         (f)   REIMBURSEMENT OF EXPENSES. Employee shall be authorized to
incur on behalf and for the benefit of, and shall be reimbursed by, the
Company for reasonable expenses, provided that such expenses are
substantiated in accordance with Company policies.

     5.  TERMINATION OF EMPLOYMENT AND SEVERANCE BENEFITS.

         (a)   TERMINATION OF EMPLOYMENT. This Agreement may be terminated
upon notice of one or more of the following events:

               (i)  The Company's determination in good faith that it is
terminating Employee for Cause (as defined in Section 6 below)("TERMINATION
FOR CAUSE");

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                   (ii)    The Company's determination that it is terminating
Employee without Cause, which determination may be made by the Company at any
time at the Company's sole discretion, for any or no reason ("TERMINATION
WITHOUT CAUSE");

                   (iii)   The effective date of a written notice sent to the
Company from Employee stating the Employee is electing to terminate his
employment with the Company ("VOLUNTARY TERMINATION");

                   (iv)    Following Employee's death or disability (as
defined in Section 7 below); or

                   (v)     A change in Employee's status such that a
Constructive Termination (as defined in Section 5(b)(iv) below) has occurred.

              (b)  SEVERANCE BENEFITS.  Employee shall be entitled to receive
severance benefits upon termination of employment only as set forth in this
Section 5(b):

                   (i)   VOLUNTARY TERMINATION.  If Employee's employment
terminates by Voluntary Termination, then Employee shall not be entitled to
receive payment of any severance benefits. Employee will receive payment(s)
for all salary and unpaid vacation accrued as of the date of Employee's
termination of employment and Employee's benefits will be continued under the
Company's then existing benefit plans and policies in accordance with such
plans and policies in effect on the date of termination and in accordance
with applicable law.

                   (ii)  INVOLUNTARY TERMINATION.  If Employee's employment
is terminated under Section 5(a)(ii) or Section 5(a)(v) above (such
termination, an "INVOLUNTARY TERMINATION"), Employee will be entitled to
receive payment of severance benefits equal to Employee's then regular
monthly salary for nine (9) months after the effective date of such
termination (the "SEVERANCE PERIOD"). Such payments shall be made ratably
over the Severance Period according to the Company's standard payroll
schedule. Employee will also be entitled to receive payment ratably over the
Severance Period of any Annual Bonus payable under Section 4(b) only to the
extent that the Annual Bonus has been earned as of the date of termination,
as determined by the Board of Directors or its Compensation Committee based
on the specific corporate and individual performance targets established for
such fiscal year. Health insurance benefits with the same coverage provided
to Employee prior to the termination (e.g. medical, dental, optical, mental
health) and in all other respects significantly comparable to those in place
immediately prior to the termination will be provided at the Company's cost
over the Severance Period.

                   (iii) TERMINATION FOR CAUSE.  If Employee's employment is
terminated for Cause, then Employee shall not be entitled to receive payment
of any severance benefits. Employee will receive payment(s) for all salary
and unpaid vacation accrued as of the date of Employee's termination of
employment and Employee's benefits will be continued under the Company's then
existing benefit plans and policies in accordance with such plans and
policies in effect on the date of termination and in accordance with
applicable law.

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             (iv) CONSTRUCTIVE TERMINATION. Constructive Termination shall be
deemed to occur if (A)(1) there is a material adverse change in Employee's
position causing such position to be of materially reduced stature or
responsibility, (2) a reduction of more than twenty percent (20%) of
Employee's base compensation unless in connection with similar decreases of
other similarly situated employees of the Company, or (3) Employee's refusal
to relocate to a facility or location more than fifty (50) miles from the
Company's current location; and (B) within the thirty (30) day period
immediately following such material change or reduction Employee elects to
terminate his employment voluntarily.

             (v) TERMINATION BY REASON OF DEATH OR DISABILITY. In the event
that Employee's employment with the Company terminates as a result of
Employee's death or Disability (as defined in Section 7 below), Employee or
Employee's estate of representative will receive all salary and unpaid
vacation accrued as of the date of Employee's death or Disability and any
other benefits payable under the Company's then existing benefit plans and
policies in accordance with such plans and policies in effect on the date of
death or Disability and in accordance with applicable law. In addition,
Employee's estate or representative will receive the amount of Employee's
salary until Disability benefits become payable (but in no event for a period
greater than 90 days) and his Annual Bonus has been earned as of the date of
Employee's death or Disability, as determined by the Board of Directors or
its Compensation Committee based on the specific corporate and individual
performance targets for such fiscal year.

      6. DEFINITION OF CAUSE. For purposes of this Agreement, "CAUSE" for
Employee's termination will exist at any time after the happening of one or
more of the following events:

         (a) Employee's willful misconduct or gross negligence in performance
of his duties hereunder, including Employee's refusal to comply in any
material respect with the legal directives of the Company's Board of
Directors so long as such directive are not inconsistent with the Employee's
position and duties, and such refusal to comply is not remedied within ten
(10) working days after written notice from the Board of Directors, which
written notice shall state that failure to remedy such conduct may result in
Termination for Cause;

         (b) Dishonest or fraudulent conduct, a deliberate attempt to do an
injury to the Company, or conduct that materially discredits the Company or
is materially detrimental to the reputation of the Company, including
conviction of a felony; or

         (c) Employee's incurable material breach of any element of the
Company's Confidential Information and Invention Assignment Agreement,
including without limitation, Employee's theft or other misappropriation of
the Company's proprietary information.

      7. DEFINITION OF DISABILITY. For purposes of this Agreement,
"DISABILITY" shall mean that Employee has been unable to perform his duties
hereunder as the result of his incapacity due to physical or mental illness,
and such inability, which continues for at least 120 consecutive calendar
days or 150 calendar days during any consecutive twelve-month period, if
shorter, after its commencement, is determined to be total and permanent by a
physician selected by the Company and its insurers and

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acceptable to Employee or to Employee's legal representative (with such
agreement on acceptability not to be unreasonably withheld).

         8.   CONFIDENTIALITY AGREEMENT.  Employee shall sign, or has signed,
a Confidential Information and Invention Assignment Agreement (the
"CONFIDENTIALITY AGREEMENT") substantially in the form attached hereto as
EXHIBIT A. Employee hereby represents and warrants to the Company that he has
complied with all obligations under the Confidentiality Agreement and agrees
to continue to abide by the terms of the Confidentiality Agreement and
further agrees that the provisions of the Confidentiality Agreement shall
survive any termination of this Agreement or of Employee's employment
relationship with the Company.

         9.   NONCOMPETITION COVENANT.  Employee hereby agrees that he shall
not, during the term of his employment pursuant to this Agreement and the
Severance Period, if any, and with respect to subsections (b) and (c) below,
for a period of twelve (12) months after termination of employment for any
or no reason, with or without Cause, do any of the following without the
prior written consent of the Board of Directors:

              (a)  COMPETE.  Carry on any business or activity (whether
directly or indirectly, as a partner, stockholder, principal, agent,
director, affiliate, employee or consultant) which is competitive with the
business conducted by the Company (as conducted now or during the term of
Employee's employment), nor engage in any other activities that conflict with
Employee's obligations to the Company.

              (b)  SOLICIT BUSINESS.  Solicit or influence or attempt to
influence any client, customer or other person either directly or indirectly,
to direct his or its purchase of the Company's products and/or services to
any person, firm, corporation, institution or other entity in competition
with the business of the Company.

              (c)  SOLICIT PERSONNEL.  Solicit or influence or attempt to
influence any person employed by the Company to terminate or otherwise cease
his employment with the Company or become an employee of any competitor of
the Company. This Section 9(c) is to be read in conjunction with Section 7 of
the Confidential Information and Invention Assignment Agreement executed by
Employee.

         10.  CONFLICTS.  Except as set forth in Section 12, Employee
represents that his performance of all terms of this Agreement will not
breach any other agreement to which Employee is a party. Employee has not,
and will not during the term of this Agreement enter into any oral or written
agreement in conflict with any of the provisions of this Agreement. Employee
further represents that he is entering into or has entered into an employment
relationship with the Company of his own free will and that he has not been
solicited as an employee in any way by the Company.

         11.  SUCCESSORS.  Any successor to the Company (whether direct or
indirect and whether by purchase, lease, merger, consolidation, liquidation
or otherwise) to all or substantially all of the Company's business and/or
assets shall assume the obligations under this Agreement and agrees expressly
to perform the obligations under this Agreement in the same manner and to the
same extent

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as the Company would be required to perform such obligations in the absence
of a succession. The terms of this Agreement and all of Employee's rights
hereunder shall inure to the benefit of, and be enforceable by, employee's
personal or legal representatives, executors, administrators, successors,
heirs, distributees, devisees and legatees.

         12. OUTSIDE ACTIVITIES. Employee shall be permitted up to four (4)
days per month to perform outside activities subject to Section 9(a) above,
such as serving as a consultant or a director to other companies or
organizations. Additionally, nothing in this Agreement will prevent Employee
from accepting speaking or presentation engagements in exchange for honoraria
or from serving on boards of charitable organizations, or from owning no more
than 1% of the outstanding equity securities of a corporation whose stock is
listed on a national stock exchange or the Nasdaq National Market.

         13. MISCELLANEOUS PROVISIONS.

                   (a) NO DUTY TO MITIGATE. Employee shall not be required to
mitigate the amount of any payment contemplated by this Agreement (whether by
seeking new employment or in any other manner), nor, except as otherwise
provided in this Agreement, shall any such payment be reduced by any earnings
that Employee may receive from any other source.

                   (b) AMENDMENTS AND WAIVERS. Any term of this Agreement may
be amended or waived only with the written consent of the parties.

                   (c) SOLE AGREEMENT. This Agreement, including any Exhibits
hereto, constitutes the sole agreement of the parties and supersedes all oral
negotiations and prior writings with respect to the subject matter hereof.

                   (d) NOTICES. Any notice required or permitted by this
Agreement shall be in writing and shall be deemed sufficient upon receipt,
when delivered personally or by a nationally-recognized delivery service
(such a Federal Express or UPS), or forty-eight (48) hours after being
deposited in the U.S. mail as certified or registered mail with postage
prepaid, if such notice is addressed to the party to be notified at such
party's address as set forth below or as subsequently modified by written
notice.

                   (e) CHOICE OF LAW. The validity, interpretation,
construction and performance of this Agreement shall be governed by the laws
of the State of California, without giving effect to the principles of conflict
of laws.

                   (f) SEVERABILITY. If one or more provisions of this
Agreement are held to be unenforceable under applicable law, the parties
agree to renegotiate such provision in good faith. In the event that the
parties cannot reach a mutually agreeable and enforceable replacement for
such provision, then (a) such provision shall be excluded from this
Agreement, (b) the balance of the Agreement shall be interpreted as if such
provision were so excluded and (c) the balance of the Agreement shall be
enforceable in accordance with its terms.

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          (g)  COUNTERPARTS. This Agreement may be executed in counterparts,
each of which shall be deemed an original, but all of which together will
constitute one and the same instrument.

          (h)  ARBITRATION. Any dispute or claim arising out of or in
connection with this Agreement will be finally settled by binding arbitration
in San Jose, California in accordance with the rules of the American
Arbitration Association by one (1) arbitrator appointed in accordance with
said rules. The arbitrator shall apply California law, without reference to
rules of conflicts of law or rules of statutory arbitration, to the
resolution of any dispute. Judgment on the award rendered by the arbitrator
may be entered in any court having jurisdiction thereof. Notwithstanding the
foregoing, the parties may apply to any court of competent jurisdiction for
preliminary or interim equitable relief, or to compel arbitration in
accordance with this paragraph, without breach of this arbitration provision.
This Section 13(h) shall not apply to the Confidentiality Agreement.

          (i)  ADVICE OF COUNSEL. EACH PARTY TO THIS AGREEMENT ACKNOWLEDGES
THAT, IN EXECUTING THIS AGREEMENT, SUCH PARTY HAS HAD THE OPPORTUNITY TO SEEK
THE ADVICE OF INDEPENDENT LEGAL COUNSEL, AND HAS READ AND UNDERSTOOD ALL OF
THE TERMS AND PROVISIONS OF THIS AGREEMENT. THIS AGREEMENT SHALL NOT BE
CONSTRUED AGAINST ANY PARTY BY REASON OF THE DRAFTING OR PREPARATION HEREOF.

                           [SIGNATURE PAGE FOLLOWS]





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     The parties have executed this Agreement the date first written above.


                                       KIVA GENETICS, INC.



                                       By: /s/ Andrew P. Sandham
                                          ---------------------------------
                                       Title:    President & COO
                                             ------------------------------

                                       Address: 2375 Garcia Ave.
                                                Mountain View, CA 94070


                                       HUGH Y. RIENHOFF, JR., M.D.


                                       Signature: /s/ Hugh Y. Rienhoff, Jr.
                                                 --------------------------

                                       Address: 1120 Dayton Avenue
                                                San Carlos, CA 94070




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