Document:

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                                                                    EXHIBIT 10.2

                                    SUBLEASE

       THIS SUBLEASE ("Sublease"), dated May 17, 2001, is entered into by and
between VIROLOGIC, INC., a Delaware corporation ("Sublandlord"), and DIADEXUS,
INC., a Delaware corporation ("Subtenant").

                                    RECITALS

       A. Sublandlord leases certain premises (the "Premises") consisting of
approximately 53,980 square feet in a building, located at 343 Oyster Point
Boulevard, South San Francisco, California, pursuant to that certain Lease dated
November 23, 1999, between ARE-Technology Center SSF, LLC, a Delaware limited
liability company, successor-in-interest to Trammell Crow Northern California
Development, Inc., as landlord (the "Master Landlord"), and Sublandlord, as
tenant, as amended by that certain First Amendment to Lease Agreement dated
February, 2000 (collectively, the "Master Lease"). The Premises is more
particularly described in the Master Lease, a copy of which is attached hereto
as Exhibit A. Capitalized terms used but not defined herein have the same
meanings as they have in the Master Lease.

       B. Sublandlord desires to sublease to Subtenant a portion of the Premises
comprising approximately 40,350 square feet and depicted on Exhibit B attached
hereto (the "Sublease Premises"), and Subtenant desires to sublease the Sublease
Premises from Sublandlord on the terms and provisions hereof.

       NOW, THEREFORE, in consideration of the mutual covenants and conditions
contained herein, Sublandlord and Subtenant covenant and agree as follows:

                                    AGREEMENT

       1. SUBLEASE PREMISES. On and subject to the terms and conditions below,
Sublandlord hereby leases to Subtenant, and Subtenant hereby leases from
Sublandlord, the Sublease Premises.

       2. TERM. This Sublease shall commence upon substantial completion of
Tenant's Work (as defined in the Master Lease) as set forth in the Work Letter
attached hereto as Exhibit C (the "Commencement Date"), provided Sublandlord has
theretofore obtained the Consent to Sublease signed by the Master Landlord in
the form of Exhibit D attached hereto, and shall expire on the last day of the
twenty-fourth (24th) month following the Commencement Date, unless sooner
terminated pursuant to any provision hereof. Subtenant shall have the right to
terminate this Sublease effective on any date on or after the first day of the
nineteenth (19th) month following the Commencement Date by providing no less
than ninety (90) days prior written notice to Sublandlord.

       3. POSSESSION/EARLY ACCESS.

              (a) The parties currently anticipate that the Commencement Date
will occur on or before August 1, 2001. If for any reason Sublandlord cannot
deliver possession of the Sublease Premises to Subtenant on or before such date,
Sublandlord shall not be subject to any

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liability therefor, except as set forth in this Section 3, nor shall such
failure affect the validity of this Sublease or the obligations of Subtenant
hereunder or extend the term hereof, provided that no Rent shall be due
hereunder until possession of the Sublease Premises has been delivered to
Subtenant. If Sublandlord is unable to deliver possession of the Sublease
Premises to Subtenant on or before November 1, 2001, for any reason other than
Master Landlord's delays in completing Landlord's Work (as defined in Exhibit
B-1 to the Master Lease) or Subtenant Delays (as defined in the Work Letter),
then Subtenant may terminate this Sublease by written notice to Sublandlord
given on or before November 10, 2001, whereupon any monies previously paid by
Subtenant to Sublandlord, including, without limitation, all or any portion of
Subtenant's Contribution, paid in accordance with the Work Letter, shall be
reimbursed to Subtenant by Sublandlord within ten (10) business days of such
termination and, following such reimbursement, the parties shall have no further
obligation to one another with respect to this Sublease. Sublandlord shall
deliver a notice to Subtenant describing any delays which Sublandlord
anticipates will result from Master Landlord's delays in completing Landlord's
Work.

              (b) Subtenant shall have the right to enter the Sublease Premises
prior to the Commencement Date for the purpose of installing cable, computer
equipment, AV equipment, PBX equipment, workstations, furniture and lab
equipment. Subtenant shall coordinate all such entries with Sublandlord so as
not to interfere with the completion of Tenant's Work. Such early entry shall be
subject to all of the terms and conditions of this Sublease, except that
Subtenant shall not be required to pay Rent on account thereof.

       4. RENT.

              (a) Commencing on the Commencement Date and continuing throughout
the term of this Sublease, Subtenant shall pay monthly rent ("Rent") to
Sublandlord in the following amounts:

                     (i) Base Rent. Subtenant shall pay to Sublandlord monthly
base rent ("Base Rent") as follows:

                      Months 1-12:        $80,700.00       ($2.00/square foot)
                      Months 13-24:       $82,718.00       ($2.05/square foot)

If, pursuant to Section 19 below, the term of this Sublease is extended for a
period beyond twenty-four (24) months, Base Rent during such extended term shall
be Fair Market Rent as determined by the parties in accordance with Section 19.

                     (ii) Additional Rent. In addition to Base Rent, Subtenant
also shall pay to Sublandlord, (a) Subtenant's proportionate share of Tenant's
Proportionate Share of Basic Operating Costs (as such terms are defined in the
Basic Lease Information and in Section 7 of the Master Lease), (b) all other
costs payable by Sublandlord with respect to the Sublease Premises under the
Master Lease, except penalties, interest and other costs and fees arising from a
default by Sublandlord under the Master Lease, and (c) any costs and expenses
applicable to the Sublease Premises which are paid directly by Sublandlord, if
any, including, but not limited to, utilities, personal property taxes and real
property taxes (collectively, "Additional Rent"). Subtenant shall pay
Subtenant's share of Basic Operating Costs and any Rent Increase as and

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when such payments are due from Sublandlord pursuant to the Master Lease, but at
least five (5) business days prior to the date Sublandlord must pay such amounts
to Master Landlord. Within ten (10) days of receipt by Sublandlord from Master
Landlord, Sublandlord shall provide to Subtenant copies of all notices relating
to Estimated Basic Operating Costs and Basic Operating Cost Adjustments
applicable to the Sublease Premises. Subtenant shall pay items of Additional
Rent other than Basic Operating costs within ten (10) days after receipt of
written demand from Sublandlord, which demand shall be accompanied by any
invoice or statement that Sublandlord received from Master Landlord relating
thereto. Promptly upon receipt from Master Landlord, Sublandlord shall provide
Subtenant with an estimate of Additional Rent for the year 2001, together with
any notices received by Sublandlord from Master Landlord with respect thereto.

                     (iii) Payment of Rent. If the Commencement Date does not
fall on the first day of a calendar month, Rent for the first month shall be
prorated on a daily basis based upon a calendar month. Rent shall be payable to
Sublandlord in lawful money of the United States, in advance, without prior
notice, demand, or offset, at least five (5) business days prior to the first
day of each calendar month during the term hereof. All Rent shall be paid to
Sublandlord at the address specified for notices to Sublandlord in Section 13
below.

              (b) Upon receipt of the Consent to Sublease executed by
Sublandlord and Master Landlord, Subtenant shall deliver to Sublandlord the sum
of Eighty Thousand Seven Hundred and No/100 Dollars ($80,700), representing the
first month's Base Rent.

              (c) In the event of any casualty or condemnation affecting the
Sublease Premises, Rent payable by Subtenant shall be abated hereunder, but only
to the extent that Rent under the Master Lease is abated, and Subtenant waives
any right to terminate this Sublease in connection with such casualty or
condemnation except to the extent the Master Lease is also terminated as to the
Sublease Premises or any portion thereof.

              (d) Base Rent and Additional Rent may be referred to herein
collectively as "Rent."

       5. SECURITY DEPOSIT. Upon execution of this Sublease, Subtenant shall
deliver to Sublandlord the sum of One Hundred Sixty-One Thousand Four Hundred
and No/100 Dollars ($161,400.00) as security for the performance of Subtenant's
obligations under this Sublease ("Security Deposit"). If Subtenant fails to pay
Rent or other charges when due under this Sublease, or fails to perform any of
its other obligations hereunder, Sublandlord may use or apply the portion of the
Security Deposit required for the payment of any Rent or other amount then due
hereunder and unpaid, for the payment of any other sum for which Sublandlord may
become obligated by reason of Subtenant's default or breach, or for any loss or
damage sustained by Sublandlord as a result of Subtenant's default or breach. If
Sublandlord so uses any portion of the Security Deposit, Subtenant shall restore
the Security Deposit to the full amount originally deposited within ten (10)
days after receipt of Sublandlord's written demand therefor. Sublandlord shall
not be required to keep the Security Deposit separate from its general accounts,
and shall have no obligation or liability for payment of interest on the
Security Deposit. The Security Deposit, or so much thereof as had not
theretofore been applied by Sublandlord, shall be returned to Subtenant within
thirty (30) days of the expiration or earlier termination of this Sublease,
provided Subtenant has vacated the Sublease Premises in accordance with the
terms of this Sublease.

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       In lieu of a cash Security Deposit, Subtenant may provide to Sublandlord
an unconditional, irrevocable letter of credit ("Letter of Credit") in the
amount set forth in this Section 5 in favor of Sublandlord and issued by a bank
located in the Bay Area and reasonably acceptable to Sublandlord ("Issuer"). The
Letter of Credit shall be in form reasonably acceptable to Sublandlord. The
Letter of Credit shall provide that draws, including partial draws, at
Sublandlord's election, will be honored upon the delivery to the Issuer of
notice signed by Sublandlord, or its authorized agent, that an event of default
has occurred under the Sublease. Any draw or partial draw of the Letter of
Credit shall not constitute a waiver by Sublandlord of its right to enforce its
other remedies hereunder, at law or in equity. If any portion of the Letter of
Credit is drawn upon, Subtenant shall, within ten (10) days after delivery of
written demand from Sublandlord, restore said Letter of Credit to its original
amount. The Letter of Credit shall be for the term of one year and automatically
shall be renewed each year for the term of sixty (60) days beyond the
termination or earlier expiration of the Sublease. The Letter of Credit will
automatically renew each year during the Sublease term unless the beneficiary
under the Letter of Credit is given at least thirty (30) days prior notice of a
non-renewal by the issuing bank, and Sublandlord shall be able to draw on the
Letter of Credit in the event of such notice.

       6. ASSIGNMENT AND SUBLETTING. Subtenant may not assign, sublet, transfer,
pledge, hypothecate or otherwise encumber the Sublease Premises, in whole or in
part, or permit the use or occupancy of the Sublease Premises by anyone other
than Subtenant, unless Subtenant has obtained Sublandlord's consent thereto,
which consent shall not be unreasonably withheld, and the consent of Master
Landlord in accordance with the terms of the Master Lease; provided, however,
that no such consent shall be required upon Subtenant's assignment or subletting
of the Sublease Premises to a Permitted Assignee (as such term is defined in
Section 21 of the Master Lease). Regardless of Sublandlord's consent, no
subletting or assignment shall release Subtenant of its obligations hereunder.
Any rent or other consideration payable to Subtenant pursuant to any sublease or
assignment permitted by this paragraph which is in excess of the Rent payable by
Subtenant to Sublandlord pursuant hereto ("Bonus Rent") shall be paid to
Sublandlord. In calculating Bonus Rent, Subtenant may first deduct from the rent
or other consideration received (a) the amortization of a reasonable brokerage
commission, (b) the cost of tenant improvements, if any, paid for by Subtenant
in connection with the assignment or subletting and (c) that portion of
Subtenant's Contribution proportionally attributable to (i) the square footage
of the Sublease Premises assigned or sublet and (ii) the duration of such
sublease or assignment.

       7. CONDITION OF SUBLEASE PREMISES/SUBLANDLORD'S WORK.

              (a) Subtenant has used due diligence in inspecting the Sublease
Premises and is satisfied with the condition of the Sublease Premises and the
property, including the environmental condition thereof. Subtenant agrees to
accept the Sublease Premises in "as-is" condition and with all faults without
any representation or warranty of any kind or nature whatsoever, or, except as
expressly set forth on Exhibit C, without any obligation on the part of
Sublandlord to modify, improve or otherwise prepare the Sublease Premises for
Subtenant's occupancy. Subtenant shall bear no responsibility for Hazardous
Materials (as defined in Section 4 of the Master Lease) existing in, on or about
the Sublease Premises at the date of this Sublease.

              (b) Sublandlord shall perform the work and make the installations
in the Sublease Premises substantially as set forth in the Work Letter attached
hereto as Exhibit C. Subtenant acknowledges that Master Landlord has not
completed Landlord's Work and that

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Sublandlord shall have no obligation to complete Landlord's Work nor any
liability arising from Master Landlord's failure to complete such work.

       8. USE. Subtenant may use the Sublease Premises only for the purposes
allowed in the Master Lease and for no other purpose. Subtenant shall promptly
comply with all applicable statutes, ordinances, rules, regulations, orders, and
restrictions of record in effect during the term of this Sublease governing,
affecting and regulating the Sublease Premises, including but not limited to the
use thereof. Subtenant shall not use or permit the use of the Sublease Premises
in a manner that will create waste or a nuisance, interfere with or disturb
other tenants in the Building or violate the provisions of the Master Lease.

       9. PARKING. Subtenant shall have a proportional interest in such parking
rights as Sublandlord has in connection with the Sublease Premises pursuant to
the Master Lease.

       10. INCORPORATION OF SUBLEASE.

              (a) All of the terms and provisions of the Master Lease, except as
provided in subsection (b) below, are incorporated into and made a part of this
Sublease and the rights and obligations of the parties under the Master Lease
are hereby imposed upon the parties hereto with respect to the Sublease
Premises, Sublandlord being substituted for the "Landlord" in the Master Lease,
and Subtenant being substituted for the "Tenant" in the Master Lease. It is
further understood that where reference is made in the Master Lease to the
"Premises," the same shall mean the Sublease Premises as defined herein; where
reference is made to the "Term Commencement Date," the same shall mean the
Commencement Date as defined herein; and where reference is made to the "Lease,"
the same shall mean this Sublease. Notwithstanding the foregoing, the term
"Landlord" in the following sections of the Master Lease (i) shall mean Master
Landlord, not Sublandlord: 8.A., 10, 24, 28, 36.J, 37.F and (ii) shall mean both
Master Landlord and Sublandlord: 18.

              (b) The following paragraphs of the Master Lease are not
incorporated herein: Basic Lease Information (except definitions that are
applicable to and appropriate in the context of this Sublease), 1, 2, 3, 6, 19,
20, 21.B., 31, 35, 37.C, D, E, G and H, Exhibit A-2, Exhibit B-1 (except to the
extent referred to in the Work Letter), Exhibit B-3, Exhibit C, Exhibit F, and
Exhibit G.

              (c) Subtenant hereby assumes and agrees to perform for
Sublandlord's benefit, during the term of this Sublease, all of Sublandlord's
obligations with respect to the Sublease Premises under the Master Lease, except
as otherwise provided herein. Subtenant shall not commit or permit to be
committed any act or omission which violates any term or condition of the Master
Lease. Except as otherwise provided herein, this Sublease shall be subject and
subordinate to all of the terms of the Master Lease.

              (d) Except as expressly set forth herein, Sublandlord hereby
grants to Subtenant all of the rights, privileges and benefits granted to or
conferred upon Sublandlord as tenant under the Master Lease, provided that
Subtenant's exercise of such rights, privileges and benefits do not result in or
cause Sublandlord to default under the Master Lease.

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       11. INSURANCE. Subtenant shall be responsible for compliance with the
insurance provisions of the Master Lease. Such insurance shall insure the
performance by Subtenant of its indemnification obligations hereunder and shall
name Master Landlord and Sublandlord as additional insureds. All insurance
required under this Sublease shall contain an endorsement requiring thirty (30)
days written notice from the insurance company to Subtenant and Sublandlord
before cancellation or change in the coverage, insureds or amount of any policy.
Subtenant shall provide Sublandlord with certificates of insurance evidencing
such coverage prior to the commencement of this Sublease.

       12. DEFAULT. In addition to defaults contained in the Master Lease,
failure of Subtenant to make any payment of Rent when due hereunder shall
constitute an event of default hereunder. If Subtenant's default causes
Sublandlord to default under the Master Lease, Subtenant shall defend, indemnify
and hold Sublandlord harmless from all damages, costs (including reasonable
attorneys' fees), liability, expenses or claims relating to such default.

       13. NOTICES. The addresses specified in the Master Lease for receipt of
notices to each of the parties are deleted and replaced with the following:

                  TO SUBLANDLORD AT:     VIROLOGIC, INC.
                                         270 East Grand Avenue
                                         South San Francisco, CA  94080
                                         Attn:  Karen Wilson/Kathy Hibbs

                  TO SUBTENANT AT:       the Sublease Premises

All notices hereunder shall be in writing and shall be sent by (a) messenger or
hand delivery; (b) reputable overnight air courier service; or (c) certified or
registered U.S. Mail, postage prepaid, return receipt requested. Notice shall be
deemed given on the earlier of the date delivered or refusal of a party to
accept delivery thereof. Each party immediately shall provide the other with a
copy of any notice of default given to or received from Master Landlord with
respect to this Sublease or the Sublease Premises.

       14. SUBLANDLORD'S OBLIGATIONS.

              (a) To the extent that the provision of any services or the
performance of any maintenance or any other act respecting the Sublease Premises
or the building in which the Sublease Premises is located (the "Building"),
including, without limitation, the performance and completion of Landlord's Work
(as defined in the Master Lease), is the responsibility of Master Landlord
(collectively "Master Landlord Obligations"), upon Subtenant's written request,
Sublandlord shall make reasonable efforts to cause Master Landlord to perform
such Master Landlord Obligations, including the commencement of appropriate
legal proceedings; provided, however, that, except to the extent resulting from
Sublandlord's breach of or default under the Master Lease which is not the
result of Subtenant's breach or default hereunder, in no event shall Sublandlord
be liable to Subtenant for any liability, loss or damage whatsoever in the event
that Master Landlord should fail to perform the same, nor shall Subtenant be
entitled to withhold the payment of Rent or to terminate this Sublease, except
to the extent Sublandlord has such a termination right under the Master Lease.
If Sublandlord is unsuccessful in obtaining the

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performance by Master Landlord of the Master Landlord Obligations in accordance
with the immediately preceding sentence, then Subtenant shall have the right,
upon prior written notice to Sublandlord, to exercise in its own name all of the
rights available to Sublandlord under the Master Lease to enforce performance on
the part of Master Landlord. It is expressly understood that the services and
repairs which are incorporated herein by reference, including but not limited to
the maintenance of exterior walls, structural portions of the roof, foundations,
walls and floors, will in fact be furnished by Master Landlord and not by
Sublandlord, except to the extent otherwise provided in the Master Lease. In
addition, Sublandlord shall not be liable for any maintenance, restoration
(following casualty or destruction) or repairs in or to the Building or Sublease
Premises, other than its obligation hereunder to use reasonable efforts to cause
Master Landlord to perform its obligations under the Master Lease. With respect
to any maintenance or repair to be performed by Master Landlord respecting the
Sublease Premises, the parties expressly agree that Subtenant shall have the
right to contact Master Landlord directly to cause it to so perform.

              (b) So long as Subtenant complies with its obligations under this
Sublease: (i) Sublandlord shall not agree to any amendment of the Master Lease
which materially affects Subtenant's rights under this Sublease; (ii)
Sublandlord shall not, without Subtenant's written consent, exercise any right
to terminate the Master Lease with respect to any period during the Sublease
term, other than on account of a default by Master Landlord under the Master
Lease, casualty or condemnation; and (iii) Sublandlord shall perform all of its
obligations under the Master Lease not assumed by Subtenant hereunder,
including, without limitation, the prompt payment to Master Landlord of all sums
paid by Subtenant to Sublandlord hereunder.

              (c) Sublandlord represents to Subtenant that (i) the Master Lease
is in full force and effect, (ii) Sublandlord is not in default under the Master
Lease and, to Sublandlord's knowledge, Master Landlord is not in default
thereunder, (iii) the Master Lease attached hereto is a full and complete copy
of the Master Lease, and (iv) as of the date of this Sublease, the Sublandlord's
leasehold estate is not encumbered by any deed of trust or mortgage financing.

              (d) Except as otherwise provided herein, Sublandlord shall have no
other obligations to Subtenant with respect to the Sublease Premises or the
performance of the Master Landlord Obligations.

       15. EARLY TERMINATION OF SUBLEASE. If, without the fault of Sublandlord,
the Master Lease should terminate prior to the expiration of this Sublease,
Sublandlord shall have no liability to Subtenant on account of such termination.
Subject to Section 14(b) above, to the extent that the Master Lease grants
Sublandlord any discretionary right to terminate the Master Lease, whether due
to casualty, condemnation, or otherwise, Sublandlord shall be entitled to
exercise or not exercise such right in its complete and absolute discretion.

       16. CONSENT OF MASTER LANDLORD AND SUBLANDLORD. If Subtenant desires to
take any action which requires the consent or approval of Sublandlord pursuant
to the terms of this Sublease, prior to taking such action, including, without
limitation, making any alterations, then, notwithstanding anything to the
contrary herein, (a) Sublandlord shall have the same rights of approval or
disapproval as Master Landlord has under the Master Lease, and (b) Subtenant
shall not take any such action until it obtains the consent of Sublandlord and
Master Landlord, as may be required under this Sublease or the Master Lease.
This Sublease shall not be effective unless

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and until the Consent to Sublease shall have been obtained. Each of Sublandlord
and Subtenant represents and warrants to the other that it has obtained all
necessary corporate approvals for the execution and delivery of this Sublease.

       17. INDEMNITY. Subtenant shall indemnify, defend, protect, and hold
Sublandlord and Master Landlord harmless from and against all actions, claims,
demands, costs, liabilities, losses, reasonable attorneys' fees, damages,
penalties, and expenses (collectively "Claims") which may be brought or made
against Sublandlord or which Sublandlord may pay or incur to the extent caused
by (i) a breach of this Sublease by Subtenant, (ii) any violation of law by
Subtenant or its employees, agents, contractors or invitees (collectively,
"Agents") relating to the use or occupancy of the Sublease Premises, (iii) any
act or omission by Subtenant or its Agents resulting in contamination of any
part or all of the Sublease Premises or the Building by Hazardous Materials or
(iv) the negligence or willful misconduct of Subtenant or its Agents.
Sublandlord shall indemnify and hold Subtenant harmless from and against any and
all loss, liability or expense, including reasonable attorneys' fees, incurred
or suffered by Subtenant on account of (i) the Sublandlord's material breach of
this Sublease, (ii) a default by Sublandlord under the Master Lease to the
extent not caused by Subtenant or (iii) Sublandlord's gross negligence of
willful misconduct with respect to the Sublease Premises or this Sublease.

       18. BROKERS. Each party hereto represents and warrants that it has dealt
with no brokers in connection with this Sublease and the transactions
contemplated herein, except Mark Pearson of CRESA Partners ("Broker"). All
Broker fees and commissions shall be paid by Sublandlord in accordance with the
terms of a separate agreement between Sublandlord and Broker. Each party shall
indemnify, protect, defend and hold the other party harmless from all costs and
expenses (including reasonable attorneys' fees) arising from or relating to a
breach of the foregoing representation and warranty.

       19. RIGHT OF FIRST OFFER.

              (a) So long as diaDexus, Inc. (or a Permitted Assignee) is the
Subtenant hereunder and occupies the entirety of the Sublease Premises, and
subject to the conditions set forth in this Section 19, prior to entering into a
sublease proposal with a third party for all or any portion of the Premises (the
"Offered Space"), Sublandlord shall deliver to Subtenant a written notice (the
"ROF Notice") informing Subtenant of Sublandlord's intent to sublease the
Offered Space to a third party at the expiration of the 24th month of the
Sublease term. Sublandlord shall deliver the ROF Notice to Subtenant not later
than the first day of the 22nd month of the Sublease term.

              (b) Within ten (10) days of receipt of the ROF Notice, Subtenant
shall notify Sublandlord in writing of Subtenant's election to sublease the
Offered Space (the "Acceptance Notice"). Failure of Subtenant to timely deliver
the Acceptance Notice shall be deemed an election by Subtenant not to sublease
the Offered Space, and Subtenant shall have no further rights to sublease any
portion of the Offered Space thereafter. Subtenant's right of first offer set
forth in this Section 19 is a one-time right.

              (c) Immediately following receipt of the Acceptance Notice,
Sublandlord and Subtenant shall negotiate in good faith the terms of the
sublease applicable to the Offered Space. The parties shall use best efforts to
finalize and execute such sublease within forty-five (45) days

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of Sublandlord's receipt of the Acceptance Notice. Such sublease shall be
subject to the following conditions:

                     (i) The term of the sublease shall be for a period not less
than six (6) months and not more than twelve (12) months.

                     (ii) Base Rent during the entire sublease term shall be the
"Fair Market Rent" for the Offered Space as agreed to by the parties. If the
parties are unable to agree on Fair Market Rent within thirty (30) days of
Sublandlord's receipt of the Acceptance Notice, then Fair Market Rent shall be
determined in accordance with subsection (d) below. In no event, however, shall
Base Rent for the Offered Space be less than the Base Rent for the Sublease
Premises for the last month of the initial Sublease term.

                     (iii) Anything herein to the contrary notwithstanding, if
Subtenant is in default under any of the terms, covenants or conditions of this
Sublease, either at the time Subtenant exercises the right of first offer or on
the commencement date of sublease applicable to the Offered Space, Sublandlord
shall have, in addition to all of Sublandlord's other rights and remedies
provided in this Sublease, the right to terminate such right of first offer upon
notice to Subtenant.

              (d) If Sublandlord and Subtenant are unable to agree on Fair
Market Rent pursuant to subsection 19(c)(ii) above, then the parties shall
submit the matter to arbitration. The arbitration shall be concluded within
ninety (90) days after the date of Subtenant's Acceptance Notice. To the extent
that arbitration has not been completed prior to the expiration of the original
Sublease term, Subtenant shall pay Base Rent at the rate applicable during the
last month of the original Sublease term, with an adjustment to be made once
Fair Market Rent is ultimately determined by arbitration. Within ten (10) days
of the expiration of the 30-day period described in subsection 19(c)(ii) above,
each party shall choose an Appraiser and shall send written notice to the other
party specifying therein the identity of the Appraiser. For purposes hereof,
"Appraiser" means a real estate broker or MAI designated appraiser, in either
case with not less than five (5) years of full time commercial appraisal or
brokerage experience in the sub-market area in which the Offered Space is
located and with no prior business dealings with the party appointing such
Appraiser. If either party fails to timely appoint an Appraiser, the sole
Appraiser appointed shall determine the Base Rent to be charged during the new
sublease term, based on the criteria described above. If two Appraisers are
appointed, they shall immediately meet and attempt to agree upon such Base Rent.
If they are unable to do so within fifteen (15) days after their first meeting,
they shall jointly appoint a third Appraiser and the third Appraiser shall
determine Fair Market Rent for the applicable extension period within ten (10)
days of his/her appointment. If the two Appraisers are unable to agree upon such
third Appraiser, either party may petition the Presiding Judge of the Superior
Court of the City and County where the Sublease Premises are located to appoint
such third Appraiser. The determination of Base Rent as provided herein shall be
binding upon the parties hereto. Promptly upon such determination, the parties
shall execute a sublease specifying the Base Rent payable during the sublease
term.

       20. RIGHT TO EXPAND SUBLEASE PREMISES.

              (a) Prior to entering into a sublease proposal with a third party
for all or any portion of the Premises, excluding the Sublease Premises (the
"Expansion Premises"),

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Sublandlord shall deliver a written notice to Subtenant setting forth the terms
upon which Sublandlord is willing to sublease such space to Subtenant (the
"Expansion Notice"). Subtenant shall notify Sublandlord in writing within ten
(10) days after receipt of the Expansion Notice of Subtenant's election to
sublease the Expansion Premises on the terms set forth in the Expansion Notice
("Subtenant's Election Notice"). Failure of Subtenant to timely deliver
Subtenant's Election Notice shall be deemed an election by Subtenant to not
sublease the Expansion Premises, and Subtenant shall have no further rights to
sublease any portion of the Expansion Premises thereafter. Subtenant's right
under this Section 20 is a one-time right. Failure of Subtenant to deliver
Subtenant's Election Notice within the required time period shall cause this
right of first offer to terminate and be of no further force or effect.

              (b) In the event Subtenant timely delivers Subtenant's Election
Notice, Landlord and Tenant shall enter into an amendment to this Sublease or a
separate lease within ten (10) business days after Sublandlord's receipt of
Subtenant's Election Notice, which amendment or separate lease shall (i) add to
the Sublease Premises the Expansion Premises, (ii) set forth the Base Rent and
other economic terms applicable to the Expansion Premises, which terms shall be
as set forth in the Notice, and (iii) provide that the term of the Expansion
Premises is coterminous with the Sublease Premises.

       21. SURRENDER OF SUBLEASE PREMISES. Upon the expiration or earlier
termination of this Sublease, Subtenant shall surrender the Sublease Premises in
the same condition as they were in on the Commencement Date, ordinary wear and
tear excepted.

       22. NO THIRD PARTY RIGHTS. The benefit of the provisions of this Sublease
is expressly limited to Sublandlord and Subtenant and their respective permitted
successors and assigns. Under no circumstances will any third party be construed
to have any rights as a third party beneficiary with respect to any of said
provisions.

       23. QUIET ENJOYMENT. Subject to Section 14(b)(ii) above, so long as
Subtenant timely pays Rent and performs its obligations under this Sublease,
Sublandlord shall take no action, or fail to take any action, which would
interfere with the right of Subtenant to peaceably have, hold and enjoy the
Sublease Premises during the Sublease term.

       24. COUNTERPARTS. This Sublease may be signed in two or more
counterparts, each of which shall be deemed an original and all of which shall
constitute one agreement.

                                      10.
<PAGE>   11

       IN WITNESS WHEREOF, the parties have executed this Sublease as of the
date first written above.

SUBLANDLORD:  VIROLOGIC, INC.,          SUBTENANT:  DIADEXUS, INC.,
a Delaware corporation                  a Delaware corporation

By: /s/ William D. Young                By: /s/ Mohan S. Iyer
   -------------------------------         -------------------------------------
Print Name: William D. Young            Print Name: Mohan S. Iyer
           -----------------------                 -----------------------------
Its: Chief Executive Officer            Its: VP of Business Development
    ------------------------------          ------------------------------------

                                      11.
<PAGE>   12

                                    EXHIBIT A

                                  MASTER LEASE

                                [to be attached]

                                      12.
<PAGE>   13

                                    EXHIBIT B

                         DEPICTION OF SUBLEASE PREMISES

                                [to be attached]

                                      13.
<PAGE>   14

                                    EXHIBIT C

                                   WORK LETTER

              1. Sublandlord shall complete the Tenant's Work (as defined in
Exhibit B-1 to the Master Lease) in accordance with the Master Lease, including,
without limitation, Exhibit B-1 thereto. Subtenant acknowledges and agrees that
Sublandlord will complete Tenant's Work in accordance with plans and
specifications dated January 30, 2001, prepared by WHL Architects ("Architect")
and approved in advance by Master Landlord (the "Plans and Specifications"). Any
and all changes to the Plans and Specifications desired by Subtenant shall be
subject to Sublandlord's approval, which approval shall not be unreasonably
withheld, and to Master Landlord's approval in accordance with the terms of the
Master Lease. Sublandlord shall not be liable to Subtenant for delays in
completion of Tenant's Work triggered by changes to the Plans and Specifications
requested by Subtenant or otherwise caused by Subtenant ("Subtenant Delays") and
any such delays shall not toll commencement of this Sublease or Subtenant's
payment of Rent hereunder, provided that Sublandlord delivers a notice to
Subtenant describing the delays which Sublandlord anticipates will result from
changes to the Plans and Specifications requested by Subtenant, promptly upon
receipt of the request for the changes from Subtenant.

              2. Subtenant shall contribute to the cost of Tenant's Work an
amount not to exceed Two Million Six Hundred Thousand and No/100 Dollars
($2,600,000.00) ("Subtenant's Contribution"). Following contribution by
Sublandlord toward the cost of Tenant's Work an amount equal to the sum of One
Million One Hundred Sixty-Five Thousand and No/100 Dollars ($1,165,000.00),
which sum shall be evidenced by copies of checks, invoices marked paid or other
evidence reasonably acceptable to Subtenant, Sublandlord may submit to
Subtenant, not more frequently than monthly, copies of all documents and
invoices submitted to Master Landlord in accordance with paragraph 2.1 of
Exhibit B-1 of the Master Lease. Within fifteen (15) days of receipt of such
documents and invoices, Subtenant shall deliver to Sublandlord the amount shown
in the request as expenditures and costs of Tenant's Work, up to the maximum of
the Subtenant's Contribution. In no event shall Subtenant be required to
contribute more to Tenant's Work than Subtenant's Contribution.

              3. As used in this Work Letter and in the Sublease, "substantial
completion" shall mean completion of Tenant's Work as certified in writing by
the Architect. Completion and/or correction of items set forth on a punch-list
shall not be required for certification of substantial completion by the
Architect.

                                      14.
<PAGE>   15

                                    EXHIBIT D

                               CONSENT TO SUBLEASE

                                [to be attached]

                                      15.<PAGE>   1

                                                                    EXHIBIT 10.3

                                    SUBLEASE

       THIS SUBLEASE ("Sublease"), dated May 25, 2001 for reference purposes
only, is entered into by and between VIROLOGIC, INC., a Delaware corporation
("Sublandlord"), and RAVEN BIOTECHNOLOGIES, INC., a Delaware corporation
("Subtenant").

                                    RECITALS

       A. Sublandlord leases certain premises consisting of approximately 24,725
square feet in a building located at 270 East Grand Avenue, South San Francisco,
California (the "Premises"), pursuant to that certain Lease dated August 27,
1997, between Britannia Pointe Grand Limited Partnership, a Delaware limited
partnership, as landlord (the "Master Landlord"), and Sublandlord, as tenant (as
amended or otherwise modified from time to time as permitted under the terms of
this Sublease, the "Master Lease"), a copy of which is attached hereto as
Exhibit A. The Premises are more particularly described in the Master Lease.
Capitalized terms used but not defined herein have the same meanings as they
have in the Master Lease.

       B. Sublandlord desires to sublease to Subtenant a portion of the Premises
comprising approximately 12,000 square feet and depicted on Exhibit B attached
hereto (the "Sublease Premises"), and Subtenant desires to sublease the Sublease
Premises from Sublandlord on the terms and provisions hereof.

       NOW, THEREFORE, in consideration of the mutual covenants and conditions
contained herein, Sublandlord and Subtenant covenant and agree as follows:

                                    AGREEMENT

       1. SUBLEASE PREMISES; SHARED USE.

              (a) On and subject to the terms and conditions below, Sublandlord
hereby leases to Subtenant, and Subtenant hereby leases from Sublandlord, the
Sublease Premises. Sublandlord and Subtenant acknowledge and agree that upon the
Commencement Date (defined below), Sublandlord shall deliver to Subtenant, and
Subtenant shall take possession of, a portion of the Sublease Premises comprised
of approximately 11,000 square feet and depicted on Exhibit B attached hereto
(the "Phase I Space"). On or before September 1, 2001, Sublandlord shall deliver
to Subtenant, and Subtenant shall take possession of, the balance of the
Sublease Premises comprised of approximately 1,000 square feet (the "Phase II
Space").

              (b) Throughout the Sublease term and at no additional cost to
Subtenant, Sublandlord shall allow Subtenant to use all office furniture and
cubicles located within the Sublease Premises and the Conference Room (defined
below) and all equipment in the glass wash area and all laboratory casework and
fume hoods located in the Sublease Premises, all of which is described on
Exhibit C attached hereto (the "Personal Property"). Subtenant accepts the
Personal Property in its "AS-IS" condition, and Subtenant acknowledges and
agrees that Sublandlord has made no representation or warranty of any kind,
express or implied, with respect to the design, operation or condition of the
Personal Property or any part thereof, its fitness for a particular purpose or
its availability throughout the term of the Sublease. Subtenant agrees, at is

                                       1.
<PAGE>   2

sole cost and expense, to maintain the Personal Property in good condition and
repair throughout the term of the Sublease, and Subtenant acknowledges and
agrees that Sublandlord shall have no obligation to repair, replace or maintain
the Personal Property during the Sublease term. Subtenant shall be solely
responsible for any and all taxes owing on the Personal Property and shall
timely pay any and all such taxes owing. Sublandlord shall retain ownership of
the Personal Property throughout the term of the Sublease, and upon the
expiration or earlier termination of the Sublease, the Personal Property shall
be surrendered to Sublandlord in the condition that it was in on the
Commencement Date, reasonable wear and tear, and damage due to casualty,
excepted.

              (c) Subtenant shall have the exclusive right to use (i) the lobby
conference room ("Room 102") from the Commencement Date until August 1, 2001,
and (ii) conference room number 152 ("Room 152") from 1:00 p.m. until 11:59
p.m., Monday through Friday, during the entire term of this Sublease. Subtenant
also shall have the nonexclusive right to use Room 102 from August 1, 2001 until
the expiration or earlier termination of this Sublease, which shared use shall
be subject to scheduling by an individual designated by Sublandlord in
Sublandlord's sole discretion. Subject to Sublandlord's prior approval, which
approval shall not be unreasonably withheld, Subtenant may furnish Room 152 with
its own furniture. Subtenant acknowledges and agrees that Sublandlord shall have
use of Room 152 from 12:00 a.m. until 12:59 p.m., Monday through Friday, and at
all hours on the weekends.

       2. TERM. This Sublease shall commence (the "Commencement Date") on the
later of: (1) June 1, 2001 and (ii) the date on which Sublandlord has (x)
re-keyed the locks on the doors to room numbers 104, 109, 112 and 153 and (y)
obtained the Master Landlord's consent to this Sublease in the form attached
hereto. This Sublease shall expire on the last day of the nineteenth (19th)
month following the Commencement Date, unless sooner terminated pursuant to any
provision hereof.

       3. POSSESSION/EARLY ACCESS.

              (a) If for any reason Sublandlord cannot deliver possession of the
Sublease Premises to Subtenant on the Commencement Date, Sublandlord shall not
be subject to any liability therefor, nor shall such failure affect the validity
of this Sublease or the obligations of Subtenant hereunder or extend the term
hereof, provided that no Rent shall be due hereunder until possession of the
Sublease Premises has been delivered to Subtenant in the condition required
pursuant to Section 2 and Section 7 of this Sublease.

              (b) Subtenant shall have the right to enter the Subleases Premises
prior to the Commencement Date for the sole purpose of installing cabling and
equipment and the Improvements (as defined in Section 7(b), below). Such early
entry shall be subject to all of the terms and conditions of this Sublease,
except that Subtenant shall not be required to pay Rent on account thereof.

       4. RENT.

              (a) Commencing on the Commencement Date and continuing throughout
the term of this Sublease, Subtenant shall pay monthly rent ("Rent") to
Sublandlord in the following amounts:

                                       2.
<PAGE>   3

                     (i) Base Rent. Subtenant shall pay to Sublandlord monthly
base rent ("Base Rent") as follows:

                     Months 1-2:        $44,000.00           ($4.00/square foot)
                     Months 3-12:       $48,000.00           ($4.00/square foot)
                     Months 13-19:      $49,800.00           ($4.15/square foot)

Notwithstanding anything contained herein to the contrary, in no event shall
Subtenant be obligated to pay to Sublandlord Base Rent on the Phase II Space
until such space has been delivered by Sublandlord to Subtenant in accordance
with this Sublease. Until possession of the Phase II Space is delivered to
Subtenant, Subtenant shall continue to pay Base Rent on the Phase I Space at the
rate of $4.00 per square foot for months 1-12 and at the rate of $4.15 per
square foot for months 13-19.

                     (ii) Additional Rent. In addition to Base Rent, Subtenant
also shall pay to Sublandlord, Subtenant's proportionate share of Operating
Expenses (as defined in Section 5.2 of the Master Lease) and real property taxes
and assessments (to the extent assessed separately from the balance of the
Property) and all other costs payable by Sublandlord with respect to the
Sublease Premises under the Master Lease, which costs accrue during the term of
this Sublease ("Additional Rent"). Subtenant also shall pay to Sublandlord as
Additional Rent any costs and expenses applicable to the Sublease Premises which
are paid directly by Sublandlord under the Master Lease, including, but not
limited to, utilities, personal property taxes and real property taxes, which
costs accrue during the term of this Sublease. Sublandlord's good faith estimate
of the amount of the monthly installments of Additional Rent for the Sublease
Premises for the year 2001 is approximately $5000.

                     (iii) Payment of Rent. If the Commencement Date does not
fall on the first day of a calendar month, Rent for the first month shall be
prorated on a daily basis based upon a calendar month. Rent shall be payable to
Sublandlord in lawful money of the United States, in advance, without prior
notice, demand, or offset, at least five (5) business days prior to the first
day of each calendar month during the term hereof. All Rent shall be paid to
Sublandlord at the address specified for notices to Sublandlord in Section 13
below.

              (b) Subtenant recognizes that late payment of any Rent will result
in administrative expenses to Sublandlord, the extent of which additional
expenses are extremely difficult and economically impractical to ascertain.
Subtenant therefore agrees that if any Rent is not paid within five (5) days of
the date when due, the amount of such Rent shall be increased by a late charge
to be paid to Sublandlord by Subtenant in an amount equal to seven percent (7%)
of the amount of the delinquent Rent.

              (c) Upon execution of this Sublease, Subtenant shall deliver to
Sublandlord the sum of Forty-Four Thousand and No/100 Dollars ($44,000.00),
representing first month's Base Rent.

              (d) In the event of any casualty or condemnation affecting the
Sublease Premises, Rent payable by Subtenant shall be abated hereunder, but only
to the extent that Rent under the Master Lease is abated, and Subtenant waives
any right to terminate this Sublease in

                                       3.
<PAGE>   4

connection with such casualty or condemnation except to the extent the Master
Lease is also terminated as to the Sublease Premises or any portion thereof.

              (e) Base Rent and Additional Rent may be referred to herein as
"Rent."

       5. SECURITY DEPOSIT. Upon execution of this Sublease, Subtenant shall
deliver to Sublandlord the sum of Ninety-Six Thousand and No/100 Dollars
($96,000.00) as a security deposit ("Security Deposit"). If Subtenant fails to
pay Rent or other charges when due under this Sublease, or fails to perform any
of its other obligations hereunder, and such failure continues beyond any
applicable cure or grace period provided hereunder, Sublandlord may use or apply
all or any portion of the Security Deposit for the payment of any Rent or other
amount then due hereunder and unpaid, for the payment of any other sum for which
Sublandlord may become obligated by reason of Subtenant's default or breach, or
for any loss or damage sustained by Sublandlord as a result of Subtenant's
default or breach. If Sublandlord so uses any portion of the Security Deposit,
Subtenant shall restore the Security Deposit to the full amount originally
deposited within ten (10) days after receipt of Sublandlord's written demand
therefor. Sublandlord shall not be required to keep the Security Deposit
separate from its general accounts and shall have no obligation or liability for
payment of interest on the Security Deposit. The Security Deposit, or so much
thereof as had not theretofore been applied by Sublandlord, shall be returned to
Subtenant within thirty (30) days of the expiration or earlier termination of
this Sublease, provided Subtenant has vacated the Sublease Premises in
accordance with the terms of this Sublease.

       In lieu of a cash Security Deposit, Subtenant may provide to Sublandlord
an unconditional, irrevocable letter of credit ("Letter of Credit") in the
amount set forth in this Section 5 in favor of Sublandlord and issued by a bank
located in the Bay Area and reasonably acceptable to Sublandlord ("Issuer"). The
Letter of Credit shall be in form reasonably acceptable to Sublandlord. The
Letter of Credit shall provide that draws, including partial draws, at
Sublandlord's election, will be honored upon the delivery to the Issuer of
notice signed by Sublandlord, or its authorized agent, that an event of default
has occurred under the Sublease. Any draw or partial draw of the Letter of
Credit shall not constitute a waiver by Sublandlord of its right to enforce its
other remedies hereunder, at law or in equity. If any portion of the Letter of
Credit is drawn upon, Subtenant shall, within ten (10) days after delivery of
written demand from Sublandlord, restore said Letter of Credit to its original
amount. The Letter of Credit shall be for the term of one year and automatically
shall be renewed each year for the term of sixty (60) days beyond the
termination or earlier expiration of the Sublease. The Letter of Credit will
automatically renew each year during the Sublease term unless the beneficiary
under the Letter of Credit is given at least thirty (30) days prior notice of a
non-renewal by the issuing bank, and Sublandlord shall be able to draw on the
Letter of Credit in the event of such notice.

       6. ASSIGNMENT AND SUBLETTING. Subtenant may not assign, sublet, transfer,
pledge, hypothecate or otherwise encumber the Sublease Premises, in whole or in
part, or permit the use or occupancy of the Sublease Premises by anyone other
than Subtenant, unless Subtenant has obtained the consent of Master Landlord in
accordance with the terms of the Master Lease. If Subtenant desires to assign,
sublet, transfer, pledge, hypothecate or otherwise encumber the Sublease
Premises, in whole or in part, or permit the use or occupancy of the Sublease
Premises by an unaffiliated third party, then, in addition to obtaining the
Master Landlord's consent, Subtenant shall obtain the consent of the
Sublandlord, which consent shall not be unreasonably

                                       4.
<PAGE>   5

withheld. Regardless of Sublandlord's approval rights, Subtenant shall provide
written notice to Sublandlord of its intent to sublet, assign or otherwise
transfer the Sublease Premises. Regardless of Sublandlord's consent, no
subletting or assignment shall release Subtenant of its obligations hereunder.
Subtenant shall pay to Sublandlord seventy-five percent (75%) of any rent or
other consideration payable to Subtenant pursuant to any sublease or assignment
permitted by this paragraph which is in excess of the Rent payable to
Sublandlord pursuant hereto, after first deducting therefrom (i) costs incurred
by Subtenant for improvements made to the subleased premises in connection with
such subletting or assignment and (ii) real estate commissions incurred by
Subtenant in connection with such assignment or subletting.

       7. CONDITION OF SUBLEASE PREMISES/SUBTENANT'S IMPROVEMENTS.

              (a) Subtenant has used due diligence in inspecting the Sublease
Premises and is satisfied with the condition of the Sublease Premises and the
Personal Property, including the environmental condition thereof. Subtenant
agrees to accept the Sublease Premises in "as-is" condition and with all faults
without any representation or warranty of any kind or nature whatsoever (except
as set forth below in this Section 7(a), or, except as expressly set forth in
paragraph 2 above), without any obligation on the part of Sublandlord to modify,
improve or otherwise prepare the Sublease Premises for Subtenant's occupancy.
Subtenant shall bear no responsibility for hazardous or toxic substances
existing in, on or about the Sublease Premises at the date of this Sublease.
Notwithstanding the foregoing, Sublandlord represents and warrants to Subtenant
that to the best of its knowledge (i) it has received no written notice from any
applicable governmental authority that the Sublease Premises are in violation of
applicable laws, including applicable environmental laws, and (ii) the plumbing,
electrical and life safety systems, and the heating, ventilation and air
conditioning systems are in working order. Sublandlord shall deliver the
Sublease Premises to Subtenant in broom clean condition.

              (b) Subtenant, at its sole cost and expense and only with the
prior written consent of the Master Landlord, may make the following
improvements to the Sublease Premises (the "Improvements"), which improvements
shall be constructed in accordance with the space plans, working drawings and
plans and specifications prepared by WHL Architects Planners Inc., Project No.
01148 (Raven Biotechnologies, Inc. Tenant Improvements), described on cover
sheet as "Issued for Permit, 05/04/01" and consisting of 20 pages in total
(collectively, the "Plans"): (i) construct a vivarium facility; (ii) construct a
demising wall and door to create a break room; and (iii) construct one
additional office. Subtenant shall complete all Improvements in a good and
workmanlike manner using new materials of quality grade and in compliance with
all applicable laws and regulations and the Master Lease.

       8. USE. Subtenant may use the Sublease Premises only for the purposes
allowed in the Master Lease and for no other purpose. Subtenant shall promptly
comply with all applicable statutes, ordinances, rules, regulations, orders,
restrictions of record, and requirements in effect during the term of this
Sublease governing, affecting and regulating its particular use of the Sublease
Premises. Subtenant shall not use or permit the use of the Sublease Premises in
a manner that will create waste or a nuisance, unreasonably interfere with or
disturb other tenants in the Building or violate the provisions of the Master
Lease.

       9. PARKING. Subtenant shall have a proportionate share of such parking
rights as Sublandlord may have in connection with the Sublease Premises pursuant
to the Master Lease.

                                       5.
<PAGE>   6

       10. INCORPORATION OF SUBLEASE.

              (a) All of the terms and provisions of the Master Lease, except as
provided in subsection (c) below, are incorporated into and made a part of this
Sublease and the rights and obligations of the parties under the Master Lease
(as incorporated herein) are hereby imposed upon the parties hereto with respect
to the Sublease Premises, Sublandlord being substituted for the "Landlord" in
the Master Lease (as incorporated herein), and Subtenant being substituted for
the "Tenant" in the Master Lease (as incorporated herein). It is further
understood that where reference is made in the Master Lease (as incorporated
herein) to the "Premises," the same shall mean the Sublease Premises as defined
herein; where reference is made to the "Commencement Date," the same shall mean
the Commencement Date as defined herein; and where reference is made to the
"Lease," the same shall mean this Sublease.

              (b) Notwithstanding the foregoing, the term "Landlord" in the
following sections of the Master Lease (as incorporated herein) shall mean
Master Landlord, not Sublandlord: 1.2, 8.1, 8.2(a), 11.1, 13.1, 13.5, 17.11 and
17.14.

              (c) Notwithstanding the foregoing, the following paragraphs of the
Master Lease are not incorporated herein: 1.1 (except the definitions of the
Building and Property contained therein); Articles 2 and 3, 5.1(a), 5.1(b),
12.2, 13.2, 13.3, 16.1, the addresses set forth in Section 17.1, 17.15, 17.16,
17.19, and Exhibits A, B, C, E, F and G.

              (d) Subtenant hereby assumes and agrees to perform for
Sublandlord's benefit, during the term of this Sublease, all of Sublandlord's
obligations with respect to the Sublease Premises under the Master Lease which
by their nature are applicable to the use and occupancy of the Sublease
Premises, except as otherwise provided herein. Subtenant shall not commit or
permit to be committed any act or omission which violates any term or condition
of the Master Lease. This Sublease shall be subject and subordinate to all of
the terms of the Master Lease.

       11. INSURANCE. Subtenant shall be responsible for compliance with the
insurance provisions of the Master Lease. Such insurance shall insure the
performance by Subtenant of its indemnification obligations hereunder and shall
name Master Landlord, Britannia Pointe Grand LLC, Slough Pointe Grand Inc.,
Britannia Management Services, Inc. and Sublandlord as additional insureds. All
insurance required under this Sublease shall contain an endorsement requiring
thirty (30) days written notice from the insurance company to Master Landlord
and Subtenant and Sublandlord before cancellation or change in the coverage,
insureds or amount of any policy. Subtenant shall provide Sublandlord with
certificates of insurance evidencing such coverage prior to the earlier of (i)
Subtenant's early entry into the Sublease Premises pursuant to Section 3 above,
or (ii) the Commencement Date. Notwithstanding anything to the contrary
contained herein, Sublandlord shall maintain, at its sole cost and expense,
property insurance covering the Personal Property.

       12. DEFAULT. In addition to defaults contained in the Master Lease,
failure of Subtenant to make any payment of Rent which failure continues beyond
the cure period provided in Section 14.1(b) of the Master Lease shall constitute
an event of default hereunder.

                                       6.
<PAGE>   7

       13. NOTICES. The addresses specified in the Master Lease for receipt of
notices to each of the parties are deleted and replaced with the following:

            TO SUBLANDLORD AT:              VIROLOGIC, INC.
                                            270 East Grand Avenue
                                            South San Francisco, CA  94080
                                            Attn:  Karen Wilson

            TO SUBTENANT (AFTER
            (COMMENCEMENT DATE) AT:         the Sublease Premises
                                            Attn:  Donald W. Perryman

            TO SUBTENANT (PRIOR TO
            (COMMENCEMENT DATE) AT:         305 Old County Road
                                            San Carlos, CA  94070
                                            Attn:  Donald W. Perryman

All notices hereunder shall be sent by (a) messenger or hand delivery; (b)
reputable overnight air courier service; or (c) certified or registered U.S.
Mail, postage prepaid, return receipt requested. Notice shall be deemed given on
the earlier of the date delivered or refusal of a party to accept delivery
thereof.

       14. SUBLANDLORD'S OBLIGATIONS.

              (a) To the extent that the provision of any services or the
performance of any maintenance or any other act respecting the Sublease Premises
or the building in which the Sublease Premises is located (the "Building") is
the responsibility of Master Landlord (collectively "Master Landlord
Obligations"), upon Subtenant's request, Sublandlord shall make reasonable
efforts to cause Master Landlord to perform such Master Landlord Obligations,
including, without limitation, a written demand of Master Landlord for such
performance; provided, however, that in no event shall Sublandlord be liable to
Subtenant for any liability, loss or damage whatsoever in the event that Master
Landlord should fail to perform the same, nor shall Subtenant be entitled to
withhold the payment of Rent or to terminate this Sublease. It is expressly
understood that the services and repairs which are incorporated herein by
reference, including but not limited to the maintenance of exterior walls,
structural portions of the roof, foundations, walls and floors, will in fact be
furnished by Master Landlord and not by Sublandlord, except to the extent
otherwise provided in the Master Lease. In addition, Sublandlord shall not be
liable for any maintenance, restoration (following casualty or condemnation) or
repairs in or to the Building or Sublease Premises, other than its obligation
hereunder to use reasonable efforts to cause Master Landlord to perform its
obligations under the Master Lease. With respect to any maintenance or repair to
be performed by Master Landlord respecting the Sublease Premises, the parties
expressly agree that, as between Sublandlord and Subtenant, Subtenant shall have
the right to contact Master Landlord directly to advise it of the problem. To
the extent that Subtenant is entitled to and receives from Master Landlord an
abatement of rent for the failure of Master Landlord to perform any Master
Landlord Obligation, Subtenant shall receive a proportionate abatement of Rent
under this Sublease.

                                       7.
<PAGE>   8

              (b) Except as otherwise provided herein, Sublandlord shall have no
other obligations to Subtenant with respect to the Sublease Premises or the
performance of the Master Landlord Obligations.

       15. EARLY TERMINATION OF SUBLEASE. If, without the fault of Sublandlord,
the Master Lease should terminate prior to the expiration of this Sublease,
Sublandlord shall have no liability to Subtenant on account of such termination.
To the extent that the Master Lease grants Sublandlord any discretionary right
to terminate the Master Lease, whether due to casualty, condemnation, or
otherwise, Sublandlord shall be entitled to exercise or not exercise such right
in its complete and absolute discretion.

       16. CONSENT OF MASTER LANDLORD AND SUBLANDLORD. Except as set forth in
paragraph 6 above, if Subtenant desires to take any action which requires the
consent or approval of Sublandlord pursuant to the terms of this Sublease, prior
to taking such action, including, without limitation, making any alterations,
then, notwithstanding anything to the contrary herein, (a) Sublandlord shall
have the same rights of approval or disapproval as Master Landlord has under the
Master Lease, and (b) Subtenant shall not take any such action until it obtains
the consent of Sublandlord and Master Landlord, as may be required under this
Sublease or the Master Lease.

       17. INDEMNITY. Subtenant shall indemnify, defend, protect, and hold
Sublandlord and Master Landlord harmless from and against all actions, claims,
demands, costs, liabilities, losses, reasonable attorneys' fees, damages,
penalties, and expenses (collectively "Claims") which may be brought or made
against Sublandlord or Master Landlord or which Sublandlord or Master Landlord
may pay or incur to the extent caused by (i) a breach of this Sublease by
Subtenant, (ii) any violation of law by Subtenant or its employees, agents,
contractors or invitees (collectively, "Agents") relating to the use or
occupancy of the Sublease Premises, (iii) any act or omission by Subtenant or
its Agents resulting in contamination of any part or all of the Sublease
Premises or the Building by any hazardous or toxic substance or hazardous waste
(as defined in the Master Lease), (iv) Subtenant's construction of the
Improvements, or (v) the negligence or willful misconduct of Subtenant or its
Agents. Sublandlord shall indemnify, defend, protect, and hold Subtenant
harmless from and against Claims which may be brought or made against Subtenant
or which Subtenant may pay or incur to the extent caused by (i) a breach of this
Sublease by Sublandlord, (ii) any act or omission by Sublandlord or its Agents
resulting in contamination of any part or all of the Sublease Premises by any
hazardous or toxic substance or hazardous waste (as defined in the Master
Lease), or (iii) the negligence or willful misconduct of Sublandlord or its
Agents.

       18. BROKERS. Each party hereto represents and warrants that it has dealt
with no brokers in connection with this Sublease and the transactions
contemplated herein, except Mark Pearson of CRESA Partners ("Broker"). All
Broker fees and commissions shall be paid by Sublandlord in accordance with the
terms of a separate agreement between Sublandlord and Broker. Each party shall
indemnify, protect, defend and hold the other party harmless from all costs and
expenses (including reasonable attorneys' fees) arising from or relating to a
breach of the foregoing representation and warranty.

                                       8.
<PAGE>   9

       19. OPTION TO EXTEND TERM.

              (a) So long as Raven Biotechnologies, Inc. (or a Permitted
Assignee) is the Subtenant hereunder and occupies the entirety of the Subleased
Premises, and subject to the conditions set forth in this Section 19, Subtenant
shall have two (2) options to extend the term of this Lease with respect to the
entirety of the Sublease Premises, for a period of three (3) months each (each
an "Extension Period"), from (x) in the case of the first option to extend, the
expiration of the original Sublease term, and (y) in the case of the second
option, from the expiration of the term of the first Extension Period, subject
to the following conditions:

                     (i) Each option to extend shall be exercised, if at all, by
written notice of exercise given to Sublandlord by Subtenant not less than
ninety (90) days prior to the expiration of the original Sublease term or the
first Extension Period, as applicable;

                     (ii) Anything herein to the contrary notwithstanding, if
Subtenant is in default under any of the terms, covenants or conditions of this
Sublease beyond any applicable cure or grace period, either at the time
Subtenant exercises an extension option or on the commencement date of the
applicable Extension Period, as applicable, Sublandlord shall have, in addition
to all of Sublandlord's other rights and remedies provided in this Sublease, the
right to terminate all options to extend upon notice to Subtenant.

              (b) In the event Subtenant exercises an option in a timely
fashion, the Sublease shall be extended for the term of the Extension Period
upon all of the terms and conditions of this Sublease, provided that the Base
Rent for the Extension Period shall be the "Fair Market Rent" for the Sublease
Premises, increased as set forth below. For purposes hereof, "Fair Market Rent"
shall be determined by Sublandlord and agreed to by Subtenant. If the parties
are unable to agree on Fair Market Rent within twenty (20) days of Subtenant's
receipt of notice of Sublandlord's determination of Fair Market Rent (the "Rent
Notice"), then Fair Market Rent shall be determined in accordance with
subsection (c) below; provided, however, that in no event shall any adjustment
of Base Rent pursuant to this paragraph result in a decrease of the Base Rent
for the Sublease Premises below the amount due from Subtenant for the last month
of the initial Sublease term or the first Extension Period, as applicable.

              (c) If Sublandlord and Subtenant are unable to agree on Fair
Market Rent pursuant to subsection 19(b) above, then the parties shall submit
the matter to arbitration. The arbitration shall be concluded within sixty (60)
days after the date of Subtenant's receipt of the Rent Notice. To the extent
that arbitration has not been completed prior to the expiration of the original
Sublease term or the first Extension Period, as applicable, Subtenant shall pay
Base Rent at the rate applicable during the last month of the original Sublease
term or the first Extension Period, as applicable, with an adjustment to be made
once Fair Market Rent is ultimately determined by arbitration. Within ten (10)
days of the expiration of the 20-day period described in subsection 19(b) above,
each party shall choose an Appraiser and shall send written notice to the other
party specifying therein the identity of the Appraiser. For purposes hereof,
"Appraiser" means a real estate broker or MAI designated appraiser, in either
case with not less than five (5) years of full time commercial appraisal or
brokerage experience in the sub-market area in which the Sublease Premises is
located and with no prior business dealings with the party appointing such
Appraiser. If either party fails to timely appoint an Appraiser, the sole
Appraiser appointed shall determine the Base Rent to be charged during the
applicable Extension Period, based on the

                                       9.
<PAGE>   10

criteria described above. If two Appraisers are appointed, they shall
immediately meet and attempt to agree upon such Base Rent. If they are unable to
do so within fifteen (15) days after their first meeting, they shall jointly
appoint a third Appraiser and the third Appraiser shall determine Fair Market
Rent for the applicable Extension Period within ten (10) days of his/her
appointment. If the two Appraisers are unable to agree upon such third
Appraiser, either party may petition the Presiding Judge of the Superior Court
of the City and County where the Sublease Premises are located to appoint such
third Appraiser. The determination of Base Rent as provided herein shall be
binding upon the parties hereto. Promptly upon such determination, the parties
shall execute an amendment to this Sublease extending the term of the Sublease
and specifying the Base Rent payable during the applicable Extension Period.

       20. SURRENDER OF SUBLEASE PREMISES. Upon the expiration or earlier
termination of this Sublease, Subtenant shall surrender the Sublease Premises in
the same condition as they were in on the Commencement Date, ordinary wear and
tear excepted and the Improvements excepted, subject to all rights of Master
Landlord under the Master Lease with respect to the Improvements.

       21. NO THIRD PARTY RIGHTS. The benefit of the provisions of this Sublease
is expressly limited to Sublandlord and Subtenant and their respective permitted
successors and assigns. Under no circumstances will any third party be construed
to have any rights as a third party beneficiary with respect to any of said
provisions, except that the Master Landlord shall be a third party beneficiary
with respect to any provisions specifically referring to Master Landlord.

       22. MASTER LANDLORD CONSENT. The terms, conditions, privileges and
obligations set forth in this Sublease are expressly contingent on Master
Landlord's written consent to this Sublease pursuant to the form of Consent
attached hereto. If Master Landlord has not so granted its consent to this
Sublease on or before May 25, 2001 or has issued its refusal to consent to the
Sublease prior to May 25, 2001, this Sublease shall be deemed terminated as of
the first to occur of the aforementioned events, in which event Sublandlord
shall promptly return to Subtenant the Security Deposit and all prepaid Rents.
Sublandlord shall use its reasonable efforts to obtain Master Landlord's consent
to the Sublease and Subtenant shall cooperate reasonably with Sublandlord in its
efforts to obtain such consent.

       23. SUBLANDLORD'S REPRESENTATIONS. Sublandlord represents and warrants as
follows: (i) the documents attached hereto as Exhibit A constitute a full and
complete copy of the Master Lease and to Sublandlord's knowledge, the Master
Lease is in full force and effect; (ii) the Master Lease has not been amended or
modified, orally or in writing; (iii) Sublandlord has possession of the Sublease
Premises; and (iv) Sublandlord is not in default under any of the terms of the
Master Lease, and to Sublandlord's knowledge, the Master Landlord is not in
default under any of the terms of the Master Lease.

       24. SUBLANDLORD'S COVENANTS. During the term of this Sublease,
Sublandlord shall comply with its obligations under the Master Lease (except to
the extent such obligations are the responsibility of Subtenant pursuant to the
terms of this Sublease) and shall not enter into any amendment to the Master
Lease that will diminish Subtenant's rights or increase Subtenant's obligations
under this Sublease. So long as Subtenant shall not be in default under any
provision of this Sublease required to be performed by Subtenant, Sublandlord
shall not disturb Subtenant

                                      10.
<PAGE>   11

in its use and occupancy of the Sublease Premises and Subtenant shall have quiet
enjoyment thereof.

       25. COUNTERPARTS. This Sublease may be signed in two or more
counterparts, each of which shall be deemed an original and all of which shall
constitute one agreement.

       IN WITNESS WHEREOF, the parties have executed this Sublease as of the
date first written above.

SUBLANDLORD:  VIROLOGIC, INC.,          SUBTENANT:  RAVEN BIOTECHNOLOGIES,
a Delaware corporation                  INC., a Delaware corporation

By: /s/ William D. Young                By: /s/ Donald W. Perryman
   -------------------------------         -------------------------------------
Print Name: William D. Young            Print Name: Donald W. Perryman
           -----------------------                 -----------------------------
Its: Chief Exeutive Officer             Its: VP CBO
    ------------------------------          ------------------------------------

                                      11.
<PAGE>   12

                           CONSENT OF MASTER LANDLORD

       Master Landlord hereby consents to the sublease of the Sublease Premises
by Sublandlord to Subtenant pursuant to the terms of this Sublease. Master
Landlord represents and warrants to Sublandlord that (i) Master Landlord knows
of no claims or defenses or circumstances, which with the passage of time, would
lead to claims or defenses by Master Landlord against Sublandlord as tenant
under the Master Lease; (ii) this Sublease does not violate any provision of the
Master Lease; (iii) no provision of this Sublease is in violation of the terms
of the Master Lease; and (iv) all rent and other charges due under the Master
Lease have been paid through and including May 31, 2001. The foregoing consent
by Master Landlord is subject to the understandings that (a) nothing contained
in the Sublease shall be construed to amend the Master Lease or to limit or
impair in any way Master Landlord's rights and remedies thereunder, (b) Master
Landlord is not hereby consenting to or agreeing to be bound by the provisions
of Section 14 or Section 24 of the Sublease, and (c) such consent does not make
Master Landlord a "party" to the Sublease for purposes of Section 18 or any
other provision of the Sublease. Master Landlord also consents to the
construction of the Improvements by Subtenant in accordance with the Plans
pursuant to Section 7(b) of the Sublease, subject to compliance with all
applicable provisions of the Master Lease relating to construction of
alterations, additions and improvements in and to the Premises, provided that
nothing in this consent shall be construed as a waiver of Master Landlord's
right of approval under the Master Lease with respect to any changes in or
additions or supplements to the Plans. Master Landlord hereby confirms that so
long as the Improvements are constructed in accordance with the Plans as
presented to and approved by Master Landlord (including any changes in or
additions or supplements to such Plans that are hereafter approved by Master
Landlord), Master Landlord will not require Sublandlord and Subtenant to remove
any of the Improvements at the expiration of the term of the Master Lease nor
require Sublandlord and Subtenant to repair and restore, at the expiration of
the term of the Master Lease, any previously existing improvements that are
modified or removed in connection with the Improvements.

MASTER LANDLORD:

BRITANNIA POINTE GRAND LIMITED PARTNERSHIP,
a Delaware limited partnership

By:  Britannia Pointe Grand, LLC,
     a California limited liability company,
     its general partner

     By: /s/ T.J. Bristow
        ------------------------------------
     Print Name: T.J. Bristow
                ----------------------------
     Its: Magager
         -----------------------------------
     Date: May 25, 2001
          ----------------------------------

                                      12.
<PAGE>   13

                                    EXHIBIT A

                                  MASTER LEASE

                                [to be attached]

                                      13.
<PAGE>   14

                                    EXHIBIT B

                         DEPICTION OF SUBLEASE PREMISES

                                      14.
<PAGE>   15

                                    EXHIBIT C

                          SCHEDULE OF PERSONAL PROPERTY

<TABLE>
<CAPTION>
    QTY      ITEM                                   V/N         S/N         SHARED
<S>          <C>                                   <C>      <C>             <C>
     1       3 DOOR TRUE BRAND REFRIGERATOR        O418      12118841

     1       LANCER WASHER                         OOO1      6E041472         X

     1       SCOTSMAN ICE MACHINE                  OOO3     926437-11A
     1       SANYO FREEZER                         O563      980100048

     1       SANYO FREEZER                         O564      961112060

     1       VWR 1680 DRIER                        OOO2       O300895         X

     1       KENMORE REFRIGERATOR                  O566        OO276

   1 SET     RACKING STORAGE SYSTEM                 NA          NA

     1       GLASSWASH CABINET                     O567         NA

  12 SETS    CUBICLE FURNITURE                      NA          NA
</TABLE>

                                      15.

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