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                                                                    EXHIBIT 10.1

                                                   Master Lease No.    200062448

                             MASTER LEASE AGREEMENT

                     LESSOR: CITICORP VENDOR FINANCE, INC.

                     LESSEE: VIROLOGIC, INC.

                         TERMS AND CONDITIONS OF LEASE

1. LEASE OF EQUIPMENT.

A. Lessor hereby leases to Lessee, and Lessee hereby leases from Lessor, the
equipment described in one or more equipment schedules (the "Schedule"), that
may hereafter be executed by Lessor and Lessee (the equipment, together with all
replacement parts, repairs, additions, substitutions and accessories shall be
referred to as the "Equipment") on the terms and conditions contained in this
Lease ("Lease") and in any Schedule. This Lease and each of the terms and
conditions herein contained will be incorporated into each Schedule in full to
the same extent as if each of the terms and conditions had been repeated and set
forth in full therein, and this Master Lease Agreement shall control and be
effective as to all such Schedules except to the extent that the Master Lease
Agreement shall control and be effective as to all such Schedules except to the
extent that the Master Lease Agreement may be inconsistent with the terms and
provisions of such Schedule, in which event the terms and provisions of such
Schedule shall prevail. Each Schedule shall constitute a separate lease and a
distinct and independent obligation of the Lessee. The parties intend this Lease
to be a "Finance Lease" under Article 2A of the Uniform Commercial Code.

B. Acceptance by Lessor shall occur only as set forth in this Section 1 and
shall continue in force with respect to all items of Equipment for the Initial
Term specified in each Schedule. Lessee agrees promptly to date, execute and
deliver to Lessor, upon delivery to Lessee of the first item of Equipment listed
on a Schedule, a confirmation of delivery on Lessor's Equipment Acceptance
Certificate ("Receipt") substantially in the form of Exhibit A attached hereto.
If Lessee does not, for any reason, date, execute and deliver to Lessor the
Receipt, within ten days after delivery of such item of Equipment, Lessee hereby
irrevocably authorizes the Lessor as its attorney-in-fact to execute the Receipt
on Lessee's behalf and to insert the date that the Equipment was delivered to
Lessee.

2. ORDER AND DELIVERY OF EQUIPMENT; LESSOR'S RIGHT TO TERMINATE. Lessee hereby
requests Lessor to order the Equipment from the Supplier named on the Schedule
and to arrange for delivery of the Equipment to Lessee at Lessee's expense, and
to lease the Equipment to Lessee. If the Equipment is not delivered to and
accepted by Lessee in form satisfactory to Lessor, within ninety (90) days from
the date Lessor orders the Equipment, Lessor may terminate the applicable
Schedule and its obligations thereunder. Lessee waives any requirement of Lessor
to furnish Lessee a copy of Lessor's purchase order for the Equipment.

3. TERM AND RENT

A. The initial term ("Initial Term") of any Schedule to which this Lease relates
shall commence on the day the first item of Equipment listed on such Schedule is
delivered to Lessee or Lessee's representative (the "Commencement Date") and
shall be of such duration as is prescribed in such Schedule. Advance Rent and
any Security Deposit as provided in any Schedule shall be payable upon the
execution of this Lease or the applicable Schedule. Interim rent shall be
payable for the period between the Commencement Date and the first day of the
month following the Commencement Date at a daily rate equal to the periodic
rental provided in any Schedule divided by the number of days in the period and
subsequent payments shall be due periodically in advance on the first day of
each successive period thereafter until all rent and other sums chargeable to
Lessee hereunder are paid in full. LESSEE'S OBLIGATION TO PAY RENT AND LESSEE'S
OTHER MONETARY OBLIGATIONS HEREUNDER ARE ABSOLUTE AND UNCONDITIONAL AND ARE NOT
SUBJECT TO ANY ABATEMENT, SET-OFF, DEFENSE OR COUNTERCLAIM FOR ANY REASON
WHATSOEVER. Any Security Deposit shall secure all obligations of Lessee
hereunder and may be applied at Lessor's discretion to any past obligation of
Lessee and to the extent not applied shall be returned to Lessee, without
interest, at the expiration of this Lease or the applicable Schedule.

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All payments of rent shall be made to Lessor at the address set forth herein or
such other address as Lessor shall designate in writing.

B. Whenever any payment is not made by Lessee when due hereunder, Lessee agrees
to pay to Lessor, not later than one month thereafter as an administrative
charge to offset Lessor's collection expenses an amount calculated at the rate
of ten cents per one dollar for each such delayed payment, plus interest on all
monies due Lessor from and after the date same is due at the rate of one and
one-third (1-1/3%) percent per month until paid, but as to each of the foregoing
in no event more than the maximum rate permitted by law.

C. As used herein, "Actual Cost" means the cost to Lessor of purchasing and
delivering the Equipment to Lessee, including taxes, transportation and other
charges. The amount of each rent payment and the Security Deposit set forth in
the applicable Schedule are based on the total cost set forth in Lessor's
purchase order for the Equipment ("Estimated Cost"), which is an estimate, and
shall be adjusted proportionately if the Actual Cost of the Equipment is greater
than said estimate. Lessee hereby authorizes Lessor to adjust upward the amounts
set forth in the Schedule when the Actual Cost is known and to add to the amount
of each rent payment any sales, use or leasing tax that may be imposed on or
measured by the rent payment. Lessor will inform Lessee of the adjustments
necessary to reflect Actual Cost. If the Actual Cost of the Equipment on any
Schedule exceeds the Estimated Cost by more than ten (10%) percent thereof
(exclusive of taxes), Lessor shall, if it desires to add to the Estimated Cost
an amount in excess of 10% of Estimated Cost, so notify Lessee in writing.
Within fifteen (15) days thereafter, Lessee at its option may terminate the
relevant Schedule by giving notice to Lessor of its intention to do so,
effective the day of such notice, subject however to the provisions of Section
3.A hereof.

D. If, at any time prior to acceptance of the Equipment leased hereunder, Lessor
makes a general pricing increase with respect to new leases (including increases
reflecting increases in financing costs or operating expenses) and desires that
such increase be reflected in the rent to be charged to Lessee under the
Schedule relating to such Equipment, then Lessor shall promptly notify Lessee of
such increase ("Increase Notification"). If such increase is in excess of ten
(10%) percent of the amount of the rent payment, Lessee at its option may
terminate the relevant Schedule; provided, however, that Lessor must be
notified, within fifteen (15) days after the date of the Increase Notification,
of Lessee's intention to do so, effective the day of such notice to Lessor. If
any increase under this Section 3.D is not in excess of ten (10%) of the rent
payment, or if Lessor is not notified of Lessee's intention to terminate the
relevant Schedule within the fifteen (15) day period set forth herein, then the
relevant Schedule shall be automatically adjusted to the new higher rent
payment.

4. NO WARRANTIES BY LESSOR, DISCLAIMER OF IMPLIED WARRANTIES AND WAIVER OF
DEFENSES. LESSOR IS NOT THE MANUFACTURER OR SUPPLIER OF OR A DEALER IN THE
EQUIPMENT, AND MAKES NO WARRANTY, EXPRESSED OR IMPLIED, TO ANYONE, AS TO THE
SUITABILITY, DURABILITY, DESIGN, CONDITION, CAPACITY, PERFORMANCE OR ANY OTHER
ASPECT OF THE EQUIPMENT OR ITS MATERIAL OR WORKMANSHIP. LESSOR FURTHER DISCLAIMS
ANY IMPLIED WARRANTIES OF ANY KIND WITH RESPECT TO THE EQUIPMENT INCLUDING THE
WARRANTY OF MERCHANTABILITY AND FITNESS FOR USE OR PURPOSE. AS TO LESSOR AND ITS
ASSIGNS, LESSEE LEASES THE EQUIPMENT "AS IS." LESSEE REPRESENTS THAT IT HAS
SELECTED THE EQUIPMENT AND THE SUPPLIER AND ACKNOWLEDGES THAT LESSOR HAS NOT
RECOMMENDED THE SUPPLIER. LESSOR SHALL HAVE NO OBLIGATION TO INSTALL, MAINTAIN,
ERECT, TEST, ADJUST, OR SERVICE THE EQUIPMENT, ALL OF WHICH LESSEE SHALL
PERFORM, OR CAUSE THE SAME TO BE PERFORMED BY QUALIFIED THIRD PARTIES. LESSOR
AND LESSOR'S ASSIGNEE SHALL NOT BE LIABLE TO LESSEE OR OTHERS FOR ANY LOSS,
DAMAGE OR EXPENSE OF ANY KIND OR NATURE CAUSED DIRECTLY OR INDIRECTLY BY ANY
EQUIPMENT HOWEVER ARISING, OR THE USE OR MAINTENANCE THEREOF OR THE FAILURE OF
OPERATION THEREOF, OR THE REPAIRS, SERVICE OR ADJUSTMENT THERETO. NO
REPRESENTATION OR WARRANTY AS TO THE EQUIPMENT OR ANY OTHER MATTER BY THE
SUPPLIER OR OTHERS SHALL BE BINDING ON THE LESSOR NOR SHALL THE BREACH OF SUCH
RELIEVE LESSEE OF, OR IN ANY WAY AFFECT, ANY OF LESSEE'S OBLIGATIONS TO LESSOR
HEREIN. IF THE EQUIPMENT IS UNSATISFACTORY FOR ANY REASON, LESSEE SHALL MAKE
CLAIM ON ACCOUNT THEREOF SOLELY AGAINST

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SUPPLIER, AND ANY OF SUPPLIER'S VENDORS, AND SHALL NEVERTHELESS PAY LESSOR ALL
RENT AND OTHER SUMS PAYABLE UNDER THIS LEASE. LESSOR HEREBY ASSIGNS TO LESSEE,
SOLELY FOR THE PURPOSE OF PROSECUTING SUCH A CLAIM, ANY OF THE RIGHTS WHICH
LESSOR MAY HAVE AGAINST SUPPLIER AND SUPPLIER'S VENDORS FOR BREACH OF WARRANTY
OR OTHER REPRESENTATIONS RESPECTING THE EQUIPMENT. REGARDLESS OF CAUSE, LESSEE
WILL NOT ASSERT ANY CLAIM WHATSOEVER AGAINST LESSOR FOR LOSS OF ANTICIPATORY
PROFITS OR ANY OTHER INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, NOR SHALL
LESSOR BE RESPONSIBLE FOR ANY DAMAGES OR COSTS WHICH MAY BE ASSESSED AGAINST
LESSEE IN ANY ACTION FOR INFRINGEMENT. LESSOR MAKES NO WARRANTY AS TO THE
TREATMENT OF THIS LEASE FOR TAX OR ACCOUNTING PURPOSES. NOTWITHSTANDING ANY FEES
WHICH MAY BE PAID BY LESSOR TO SUPPLIER OR ANY AGENT OF SUPPLIER, LESSEE
UNDERSTANDS AND AGREES THAT NEITHER SUPPLIER NOR ANY AGENT OF SUPPLIER IS AN
AGENT OF LESSOR OR IS AUTHORIZED TO WAIVE OR ALTER ANY TERM OF CONDITION OF THIS
LEASE.

5. JURISDICTION AND VENUE. LESSEE CONSENTS TO THE PERSONAL JURISDICTION OF THE
FEDERAL AND STATE COURTS OF THE STATE OF NEW JERSEY WITH RESPECT TO ANY ACTION
ARISING OUT OF THIS LEASE OR THE EQUIPMENT, PROVIDED, HOWEVER, LESSOR MAY, IN
ITS SOLE DISCRETION, ENFORCE THIS LEASE IN ANY COURT HAVING LAWFUL JURISDICTION
THEREOF. THIS MEANS ANY LEGAL ACTION ARISING OUT OF THIS LEASE MAY BE FILED IN
NEW JERSEY, AND LESSEE MAY BE REQUIRED TO DEFEND AND LITIGATE ANY SUCH ACTION IN
NEW JERSEY. LESSEE AGREES THAT SERVICE OF PROCESS IN ANY SUIT MAYBE MADE BY
CERTIFIED MAIL, RETURN RECEIPT REQUESTED, ADDRESSED TO THE LESSEE AT THE ADDRESS
SET FORTH HEREIN.

6. TITLE; PERSONAL PROPERTY. The Equipment is, and shall at all times be owned
by Lessor and Lessee shall have no interest in the Equipment except that of
Lessee and Lessee shall have the right to purchase or otherwise acquire title to
or ownership of any of the Equipment. If Lessor supplies Lessee with labels
indicating that the Equipment is owned by Lessor, Lessee shall affix such labels
to and keep them in a prominent place on the Equipment. Lessee hereby authorizes
Lessor to insert in this Lease the serial numbers, and other identification data
of Equipment when determined by Lessor. To protect Lessor's rights in the
Equipment in the event this Lease is determined to be a security agreement,
Lessee hereby grants to Lessor a security interest in the Equipment described
herein and in the Schedules or in any invoices that contain descriptions of the
Equipment, and all proceeds and products thereof. Lessee hereby authorizes
Lessor, at Lessee's expense, to cause this Lease, or any statement or other
instrument in respect of this Lease showing the interest of Lessor in the
Equipment, including Uniform Commercial Code financing statements, to be filed
or recorded, and grants Lessor and its agents the right to execute Lessee's name
thereto. Lessee agrees to execute, deliver and file any statement or instrument
requested by Lessor for such purpose, and if certificates of title are issued or
outstanding with respect to any of the Equipment, Lessee will cause the interest
of Lessor to be properly noted thereon, and agrees to pay or reimburse Lessor
for any searches, filings, recordings, stamp fees or taxes related to the filing
or recording of any such instrument or statement, plus Lessor's handling
charges. Lessee shall, at its expense, protect and defend Lessor's title against
all persons claiming against or through Lessee, at all times keeping the
Equipment free from any legal process or encumbrance whatsoever including but
not limited to liens, attachments, levies and executions, and shall give Lessor
immediate written notice thereof and shall indemnify Lessor from any loss caused
thereby. Lessee shall, upon Lessor's request, execute or obtain from third
parties and deliver to Lessor such estoppel certificates, landlord's waivers and
such further instruments and assurances as Lessor deems necessary or advisable
for the confirmation or perfection of Lessor's rights hereunder. The Equipment
is, and shall at all times be and remain, personal property notwithstanding that
the Equipment or any part thereof may now be or hereafter become, in any manner,
affixed or attached to real property or any improvements thereon. Lessee agrees
to pay Lessor a non-refundable fee of $250 for Lessor's documentation costs,
including without limitation the preparation of financing statements.

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7. MAINTENANCE, USE AND LOCATION. Lessee shall, at its own cost and expense,
maintain the Equipment in good operating condition and repair and protect the
Equipment from deterioration other than normal wear and tear; the Equipment is
to be used for business purposes only in the regular course of its business,
within its normal operating capacity, without abuse; shall comply with all laws,
ordinances, regulations, requirements and rules with respect to the use,
maintenance and operation of the Equipment; shall not make any modification,
alteration or addition to the Equipment without the prior written consent of
Lessor, which shall not be unreasonably withheld, except for engineering changes
recommended by and made by the manufacturer; shall install on the Equipment all
engineering changes offered by the manufacturer without charge which enhance the
safety of the Equipment; shall not so affix the Equipment to realty as to change
its nature to real property or a fixture; and shall keep the Equipment at the
location shown herein, and shall not remove the Equipment without prior written
consent of Lessor. Lessee will grant access to the Equipment to Lessor, Lessor's
designee, and the manufacturer during normal working hours for inspection,
repair, preventative maintenance, installation of engineering changes and for
any other reasonable purpose. Lessee shall during the term of this Lease, at its
own expense, enter into and maintain in force a contract with the manufacturer
or other acceptable maintenance company covering the maintenance of the
Equipment and furnish a copy thereof to Lessor upon request. If Lessor incurs
any costs or expenses to bring the Equipment up to good working order and
appearance, Lessee shall immediately reimburse Lessor for all such costs or
expenses.

8. REDELIVERY; RENEWAL TERM. After the Initial Term, and after each renewal term
thereafter, this Lease shall be automatically renewed for a term of six months,
unless Lessee shall give Lessor written notice of termination at least one
hundred twenty (120) days before the expiration of the then current term. Within
ten (10) days of expiration or earlier termination of this Lease, Lessee shall
return the Equipment and all cable, wiring, connectors, accessories and
attachments thereto, freight and insurance prepaid, to Lessor in good repair,
condition and working order, ordinary wear and tear resulting from proper use
thereof only excepted. Lessee shall have the Equipment certified as acceptable
for the manufacturer's standard maintenance contract and such certification
shall be presented to Lessor at least fourteen (14) days prior to redelivery to
Lessor. Lessor shall have the right, by notice to Lessee, and at Lessee's cost,
to make all arrangements for the discontinuance, disassembly, packing and
transportation of each item of Equipment and to designate a redelivery location.
If Lessee fails to give Lessor the required notice or to return the Equipment as
provided herein, this Lease shall renew for additional terms of 120 days each at
a periodic rent equal to the periodic rent stated herein. Nothing contained
herein is intended to relieve Lessee of its obligations to return the Equipment
to Lessor as provided herein or restrict Lessor's right to recover the Equipment
in the event of the failure of Lessee to so return the Equipment at the
expiration or termination of this Lease. If requested by Lessor, Lessee shall
store the Equipment at Lessee's premises for a period of up to ninety (90) days
at no cost to Lessor.

9. RISK OF LOSS. Lessee shall bear all risks of loss or damage to Equipment from
any cause from the date of the shipment of the Equipment to Lessee until its
return to Lessor. The occurrence of any such loss or damage shall not relieve
Lessee of any obligation hereunder. Lessee shall notify Lessor of any damage to
or destruction of the Equipment. In the event of loss or damage, Lessee, at
Lessor's sole option, shall: (a) repair the damaged Equipment; or (b) replace
lost or unrepairable Equipment with substantially identical Equipment in good
condition and working order with documentation creating clear title thereto in
Lessor; or (c) pay to Lessor the present value of the unpaid balance of the rent
to become due under this Lease plus Lessor's anticipated residual value of the
Equipment at the scheduled expiration of this Lease, all discounted at six (6%)
percent per annum to the date of loss. Upon Lessor's receipt of replacement
Equipment or payment as provided in (b) or (c) hereof, Lessee and/or Lessee's
insurer shall be entitled to Lessor's interest in said item for salvage
purposes, in its then condition and location, without warranty, express or
implied.

10. INSURANCE. Lessee shall keep the Equipment insured against all risks of loss
or damage from every cause whatsoever for not less than the full replacement
value thereof, and shall carry public liability and property damage insurance
covering the Equipment and its use in amounts customary for such Equipment. All
such insurance shall be in form and amount and with companies acceptable to
Lessor and name Lessor and its assignee as loss payees, as their interests may
appear with respect to property damage coverage, and as additional insureds with
respect to public liability coverage. Lessee shall pay the premiums therefore
and deliver said policies, or duplicates thereof or certificates of coverage
therefore to Lessee, with long form Lender's loss payable endorsement upon the
policy or policies or by independent instrument, that provides

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Lessor a right to thirty (30) days' written notice before the policy can be
altered or canceled and the right without obligation to payment of premium.
Should Lessee fail to provide such insurance coverage, Lessor may obtain such
coverage for its benefit or for the benefit of Lessee and charge Lessee
therefore. Lessee hereby appoints Lessor as Lessee's attorney-in-fact to make
claim for, receive payment of, and execute and endorse all documents, checks, or
drafts for loss or damage under any said insurance policies and to apply the
proceeds in furtherance of the exercise of Lessor's options as provided herein.

11. TAXES AND CHARGES. This Lease is intended to be a net lease, and all
payments hereunder are intended to be net to Lessor to the extent permitted by
applicable law. Lessee shall pay directly (or, at Lessor's option, reimburse
Lessor for) all license fees, assessments and other government charges, and all
sales, use, excise, franchise, personal property and any other similar tax or
taxes (herein collectively called "Charges") now or hereafter imposed, levied or
assessed by any state, federal or local government or agency upon any of the
Equipment or upon the leasing, purchase, ownership, use, possession, financing
or operation thereof, or upon the receipt of rental payments therefore, even if
Lessee's status provides for its exemption from the Charges (excluding income
and gross receipt taxes on rental payments, except any such tax on rental
payments which is a substitution for, or relieves Lessee from, the payment of
taxes which Lessee would otherwise be obligated to pay or reimburse Lessor as
herein provided) before the same shall become in default or subject to the
payment of any penalty or interest. Lessee shall supply Lessor with receipts or
other evidence of payment of all Charges as may reasonably be requested by
Lessor. Lessee shall further comply with all state and local laws requiring the
filing of ad valorem or other tax returns relating to any Charges. Lessee shall
notify the Lessor of the imposition of, or, to Lessee's knowledge, the proposed
imposition of, any Charges by supplying to Lessor (within five (5) days after
receipt thereof by Lessee) a copy of the invoice or other documents respecting
such Charges. Unless otherwise directed by Lessor in writing, Lessor shall pay
all personal property taxes with respect to the Equipment and Lessee shall
reimburse Lessor therefore upon demand.

12. LEASE IRREVOCABILITY AND OTHER COVENANTS AND REPRESENTATIONS OF LESSEE.
LESSEE AGREES THAT THIS LEASE IS IRREVOCABLE FOR THE FULL TERM HEREOF AND THE
LESSEE'S OBLIGATIONS UNDER THIS LEASE ARE ABSOLUTE AND SHALL CONTINUE WITHOUT
ABATEMENT AND REGARDLESS OF ANY DISABILITY OF LESSEE TO USE THE EQUIPMENT OR ANY
PART THEREOF BECAUSE OF ANY REASON INCLUDING, BUT NOT LIMITED TO WAR, ACT OF
GOD, GOVERNMENTAL REGULATIONS, STRIKE, LOSS, DAMAGE, DESTRUCTION, OBSOLESCENCE,
FAILURE OF OR DELAY IN DELIVERY, FAILURE OF THE EQUIPMENT TO OPERATE PROPERLY,
TERMINATION  BY OPERATION OF LAW, OR ANY OTHER CAUSE. LESSEE AGREES TO DELIVER
TO LESSOR ANNUAL FINANCIAL STATEMENTS AND SUCH INTERIM STATEMENTS, AS LESSOR
REQUESTS. LESSEE REPRESENTS THAT THIS LEASE HAS BEEN DULY AUTHORIZED BY ALL
NECESSARY ACTION ON ITS PART, IS A VALID, BINDING AND LEGALLY ENFORCEABLE
OBLIGATION OF LESSEE IN ACCORDANCE WITH ITS TERMS AND IS NOT IN ANY RESPECT
INCONSISTENT WITH LESSEE'S CHARTER OR BY-LAWS OR ANY LAW, REGULATION, ORDER OR
AGREEMENT BINDING UPON LESSEE; AND THE EQUIPMENT SHALL BE USED BY LESSEE SOLELY
FOR BUSINESS PURPOSES AND THAT ALL FINANCIAL AND OTHER INFORMATION SUBMITTED TO
LESSOR WAS AND WILL BE TRUE AND CORRECT.

13. INDEMNITY. Lessee shall indemnify and hold Lessor harmless from and against
any and all claims, actions, suits, proceedings, costs, expenses, damages and
liabilities, pre and post judgment attorneys' fees and costs, arising out of,
connected with, or resulting from the Equipment or this Lease, including without
limitation, the manufacture, selection, delivery, possession, use, lease,
operation, removal or return of the Equipment.

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14. DEFAULT AND REMEDIES.

A. The occurrence of any one of the following events shall be deemed an "Event
of Default" under this Lease: (a) Lessee fails to pay any rent or any other
payment hereunder when due; or (b) Lessee fails to pay, when due, any
indebtedness to Lessor arising independently of this Lease, including but not
limited to, any other leases between Lessor and Lessee, and such default shall
continue for five (5) days; or (c) Lessee fails to perform any of the terms,
covenants or conditions of this Lease or any other lease between Lessor and
Lessee, other than as provided in (a) or (b) above, and such failure continues
after ten (10) days written notice; or (d) any representation of Lessee
contained in this Lease or any other related agreement, or in any credit or
other information submitted to Lessor in connection with this transaction is
untrue or incorrect; or (e) Lessee sells substantially all of its assets out of
the ordinary course of business, merges or consolidates with any other person,
or, sustains a change in its ownership of more than 20% in the aggregate; or (f)
Lessee becomes insolvent or makes an assignment for the benefit of creditors; or
(g) a receiver, trustee, conservator or liquidator of Lessee or of all or a
substantial part of its assets is appointed with or without the application or
consent of Lessee; or (h) a petition is filed by or against Lessee under the
Bankruptcy Code or any amendment thereto, or under any other insolvency law or
laws, providing for the relief to debtors.

B. Upon an Event of Default, Lessor may, to the extent permitted by applicable
law, exercise any one or more of the following remedies:

        (i) Terminate this Lease with respect to all or any part of Equipment;

        (ii) Recover from Lessee all rent and other amounts then due and as they
shall thereafter become due hereunder;

        (iii) Take possession of any or all items of Equipment on any Schedule,
wherever the same may be located, without demand or notice, without any court
order or other process of law and without liability to Lessee for any damages
occasioned by such taking of possession, and any such taking of possession shall
not constitute a termination of this Lease;

        (iv) Declare the entire unpaid balance of rent and other amounts for the
unexpired term of this Lease immediately due and payable and recover from
Lessee, with respect to any and all items of Equipment and with or without
repossessing the Equipment the sum of:

                1. The unpaid balance of all rent and other amounts due for the
balance of the term of this Lease, discounted at four (4%) percent per annum;
and,

                2. Lessor's anticipated residual recovery from the Equipment at
the scheduled expiration of the initial term of this Lease, discounted at four
(4%) percent per annum; provided, however, that upon repossession or surrender
of Equipment, Lessor may sell, lease or otherwise dispose of Equipment in a
commercially reasonable manner, with or without notice and on public or private
bid, and if so, shall apply the net proceeds thereof (after deducting all
expenses, including attorneys' fees and costs incurred in connection therewith),
to the sum of (1) and (2) above;

        (v) Declare any other leases between Lessor and Lessee in default and
exercise with respect to such leases any of the remedies provided for herein;

        (vi) Pursue any other remedy available at law or in equity, including
but not limited to seeking damages or specific performance and/or obtaining an
injunction.

C. Lessee shall be liable and shall pay to Lessor all expenses incurred by
Lessor in connection with the pre and post judgment enforcement of any of the
Lessor's remedies, including all expenses of repossessing, storing, shipping,
repairing, and selling the Equipment, and Lessor's reasonable attorneys' fees
and costs. Lessor and Lessee acknowledge the difficulty in establishing a value
for the unexpired lease term and owing to such difficulty agree that the
provisions of this paragraph 14 represent an agreed measure of damages and are
not to

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be deemed a forfeiture or penalty.

D. All remedies of Lessor hereunder are cumulative, are in addition to any
other remedies provided for by law, and may, to the extent permitted by law, be
exercised concurrently or separately. The exercise of any one remedy shall not
be deemed to be an election of such remedy or to preclude the exercise of any
other remedy. No failure on the part of the Lessor to exercise and no delay in
exercising any right or remedy shall operate as a waiver thereof or modify the
terms of this Lease. A waiver of default shall not be a waiver of any other or
subsequent default. If this Lease is determined to be subject to any laws
limiting the amount chargeable or collectible by Lessor then Lessor's recovery
shall in no event exceed the maximum amounts permitted by law.

15. ASSIGNMENT, WAIVER OF DEFENSES: QUIET ENJOYMENT. LESSEE SHALL NOT ASSIGN,
TRANSFER, PLEDGE, HYPOTHECATE, OR OTHERWISE DISPOSE OF THIS LEASE OR ANY
INTEREST HEREUNDER NOR SUBLET OR LEND EQUIPMENT OR PERMIT IT TO BE USED BY
ANYONE OTHER THAN LESSEE OR LESSEE'S EMPLOYEES WITHOUT LESSOR'S PRIOR WRITTEN
CONSENT. Lessor may, without notice or consent, assign or transfer this Lease or
grant a security interest in any Equipment, any rentals, or any other sums due
or to become due hereunder, and in such event Lessor's assignee, transferee or
grantee shall have all the rights, powers, privileges, and remedies of Lessor
hereunder. Lessee agrees that, following its receipt of notice of any assignment
by Lessor of this Lease or the Rental Payments payable hereunder, it will pay
the Rental Payments due hereunder directly to the assignee (or to whomever the
assignee shall designate). Lessee agrees that no assignee of Lessor shall be
bound to perform any duty, covenant, condition or warranty attributable to
Lessor, and Lessee further agrees not to raise any claim or defense arising out
of this Lease or otherwise which it may have against Lessor as a defense,
counterclaim, or offset to any action by an assignee or secured party hereunder.
Upon Lessor's request, Lessee will acknowledge to any assignee receipt of
Lessor's notice of assignment. Nothing contained herein is intended to relieve
Lessor of any of its obligations. Provided Lessee is not in default hereunder,
Lessee shall quietly use and enjoy the Equipment, subject to the terms hereof.

16. PERFORMANCE BY LESSOR OF LESSEE'S OBLIGATIONS. In the event Lessee fails to
comply with any provisions of this Lease, Lessor shall have the right, but shall
not be obligated, to effect such compliance on behalf of Lessee upon ten (10)
days prior written notice to Lessee. In such event, all monies expended by, and
all expenses of Lessor in effecting such compliance shall be deemed to be
additional rent, and shall be paid by Lessee to Lessor at the time of the next
rent payment, together with interest at the rate of one and one-third (1-1/3%)
percent per month but in no event more than the maximum permitted by law.

17. GOVERNING LAW; JURISDICTION AND VENUE; WAIVER OF TRIAL BY JURY AND RIGHTS
AND REMEDIES UNDER THE UNIFORM COMMERCIAL CODE. THIS LEASE SHALL BE GOVERNED
BY, AND CONSTRUED ACCORDING TO THE LAWS OF THE STATE OF NEW JERSEY. TO THE
EXTENT PERMITTED BY LAW, LESSEE WAIVES TRIAL BY JURY IN ANY ACTION RELATED TO
OR ARISING OUT OF THIS LEASE OR THE EQUIPMENT BY OR AGAINST LESSOR HEREUNDER.
LESSEE HEREBY WAIVES ANY AND ALL RIGHTS AND REMEDIES GRANTED LESSEE BY SECTIONS
2A-508 THROUGH 2A-522 OF THE UNIFORM COMMERCIAL CODE. LESSEE WAIVES THE RIGHT
TO FILE ANY AMENDMENTS OR TERMINATIONS OF FINANCING STATEMENTS WITHOUT LESSOR'S
SIGNATURE.

18. GENERAL. This Lease shall inure to the benefit of and is binding upon the
heirs, legatees, personal representatives, successors and assigns of the parties
hereto. Time is of the essence of this Lease. This Lease and any Schedule shall
be effective when executed by a duly authorized officer of Lessor. This Lease
and any Schedule contains the entire agreement between Lessor and Lessee with
respect to the subject matter hereof, and all negotiations and understandings
have been merged herein. No modification of this Lease shall be effective unless
in writing and executed by an executive officer of Lessor. All covenants and
obligations of Lessee to be performed pursuant to this Lease, including all
payments to be made by Lessee hereunder, shall survive the expiration or earlier
termination of this Lease. If more than one Lessee is named in this Lease, the
liability of each shall be joint and several. In the event any provision of this
Lease shall be unenforceable, then such provision shall be deemed deleted,
however, all other provisions hereof shall remain in full force and effect.
Service of all notices under this Lease shall be sufficient if given personally,
mailed to the party intended at its address set forth herein, or at such other
addresses said party may provide in writing from time to

                                    -7 of 8-
<PAGE>
time by certified mail, or overnight mail service. Any such notice sent by
certified mail to said address shall be deemed effective five (5) days after it
is deposited in the United States mail, duly addressed and with postage prepaid,
and any notice given by delivery or overnight mail shall be deemed effective
when received. This lease, any Schedule and all related documents, including (a)
amendments, addendums, consents, waivers and modifications which may be executed
contemporaneously or subsequently herewith, (b) documents received by the Lessor
from the Lessee, and (c) financial statements, certificates and other
information previously or subsequently furnished to the Lessor, may be
reproduced by the Lessor by any photographic, photostatic, microfilm,
micro-card, miniature photographic, compact disk reproduction or other similar
process and the Lessor may destroy any original document so reproduced. The
Lessee agrees and stipulates that any such reproduction shall, to the extent
permitted by applicable law, be admissible in evidence as the original itself in
any judicial or administrative proceeding (whether or not the original is in
existence and whether or not the reproduction was made by the Lessor in the
regular course of business) and that any enlargement, facsimile or further
reproduction of the reproduction shall likewise be admissible in evidence.

        IN WITNESS WHEREOF, the parties have executed this Lease as of 4/21,
2002.

                                        LESSEE: VIROLOGIC, INC.

                                        PLACE OF ORGANIZATION: CALIFORNIA

ATTEST: /s/ [SIGNATURE ILLEGIBLE]       BY: /s/ KAREN WILSON
       ----------------------------        -------------------------------------

             Secretary                  Title: CFO
                                              ----------------------------------

                                        LESSOR: CITICORP VENDOR FINANCE, INC.
                                        700 EAST GATE DRIVE
                                        MT. LAUREL, NJ 08054-5404

                                        BY: /s/ BONNIE PSZAEGOWSKI
                                           -------------------------------------

                                        Title: AM
                                              ----------------------------------

                                   - 8 of 8 -
<PAGE>
                          CITICORP VENDOR FINANCE, INC.

                        EQUIPMENT SCHEDULE NO. 200062448

This Equipment Schedule No 200062448 ("Equipment Schedule") to that certain
Master Lease Agreement Number 200062448 (hereinafter called the "Master Lease")
between Lessor and the Lessee whose name appears below, together with the
Master Lease, constitutes a lease of the Equipment described below
(hereinafter, collectively, this "Lease"). All the terms and conditions of the
Master Lease are incorporated herein as if all said terms and conditions were
fully set forth herein. All capitalized terms used but not defined herein shall
have the meanings given such terms in the Master Lease. It is the intent of
the parties that this Equipment Schedule be separately enforceable as a
complete and independent lease, independent of all other Equipment Schedules to
the Master Lease.

<Table>
<Caption>
------------------------------------------------------------------------------------------------------------------------------------
LESSEE:                                       SUPPLIER
VIROLOGIC, INC.                               APPLERA CORPORATION dba APPLIED BIOSYSTEMS GROUP
345 OYSTER POINT BLVD.                        301 MERRITT 7
SOUTH SAN FRANCISCO, CA 94080                 NORWALK, CT 06856
------------------------------------------------------------------------------------------------------------------------------------

<S>  <C>                                      <S>                <S>
------------------------------------------------------------------------------------------------------------------------------------
QTY   DESCRIPTION OF EQUIPMENT (INDICATE IF USED EQUIPMENT)       (MODEL NO.)
     (SERIAL NO.)
------------------------------------------------------------------------------------------------------------------------------------
1    Refurbished 3700 DNA Analyzer Sequencing including extended service
------------------------------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------------------------------
EQUIPMENT LOCATION IF DIFFERENT THAN ABOVE:

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

------------------------------------------------------------------------------------------------------------------------------------
INITIAL TERM         RENTAL              TOTAL NO. AND AMOUNT OF EACH RENTAL            ADVANCE RENTAL PAYMENT             SECURITY
OF LEASE             PAYMENTS            PAYMENT DURING INITIAL TERM OF LEASE           TO BE APPLIED TO                   DEPOSIT
                     PAYABLE                                                            THE FIRST 1 MONTH(S) AND
36 MONTHS            PERIODICALLY        1 monthly payment of $30,634.94 followed by:                                      $N/A
                     AS FOLLOWS          35 monthly payments of $7,134.94               THE LAST 0 MONTH(S)
                                                                                        RENTAL
                     x MONTHLY
                    ---                                                                 PAYMENTS TOTALING
                       QUARTERLY                                                        $30,634.94
                    ---                                                                 (ADVANCE PAYMENTS MUST
                       OTHER                                                            ACCOMPANY LEASE
                    ---                                                                 APPLICATION)
------------------------------------------------------------------------------------------------------------------------------------
</Table>

MONTHLY RENT: The first payment of monthly rent is due and payable on the
Commencement Date. Subsequent payments of monthly rent are due and payable on
the first day of each succeeding month.

CHATTEL PAPER: To the extent this Lease may be considered "chattel paper" as
defined in the Uniform Commercial Code, only Counterpart Number One of any of
the manually executed counterparts of this Equipment Schedule incorporating the
terms of the Master Lease Agreement, shall constitute the original of this
Lease, and no interest in this Lease may be created or transferred except by
transfer of possession of that counterpart.

RENTAL PAYMENTS: The rental payments are predicated on the 3 Year Interest SWAP
Rate of 4.05% as of 2/21/02. The final rate (and payment) will be adjusted
upward and will fix upon the commencement of the Lease, based upon changes in
the 3 Year Interest SWAP Rates in effect at that time. Interest SWAP Rates are
published daily in the Federal Reserve Statistical Release H-15, which can be
found at:

         http://www.federalreserve.gov/releases/H15/update/h15upd.htm.

MAINTENANCE/SUPPLIES/SERVICES: Lessee agrees to pay the monthly payments under
this Lease which may include charges (the "Charges") for supplies ("Supplies"),
maintenance and/or warranty services (collectively the "Services") to be
furnished by Supplier to Lessee for use with the Equipment. Lessee agrees that
Lessor is not a manufacturer or supplier of the Supplies or Services and Lessee
will look only to Supplier for the furnishing of Supplies and the performance
of Services. Lessee further agrees that its obligations under this Lease are
unconditional notwithstanding any breach by Supplier of any obligation to
Lessee to furnish the Supplies and/or provide the Services.

EQUIPMENT SCHEDULE ACCEPTED BY:

CITICORP VENDOR FINANCE, INC. (Lessor)       Virologic, Inc. (Lessee)

By: /s/ BONNIE PSZAEGOWSKI                   By: /s/ KAREN WILSON
    -----------------------------------         --------------------------------
          (Authorized Signature)                   (Authorized Signature)

   /s/  Bonnie Pszaegowski, AM, 6-11-02      Karen Wilson CFO 4/21/02
   ------------------------------------      -----------------------------------
            (Name/Title/Date)                        (Name/Title/Date)
                                             Attest:
                                                    ----------------------------

EQUIPMENT SCHEDULE COUNTERPART NO. 1 OF 1
<PAGE>
                                   EXHIBIT A

                        EQUIPMENT ACCEPTANCE CERTIFICATE

                     CERTIFICATE OF DELIVERY AND ACCEPTANCE

                      EQUIPMENT SCHEDULE NUMBER: 200062448

                       DATED:          4-21-02
                             ----------------------------

      In compliance with the terms, conditions and provisions of the Master
Lease Agreement Number 200062448 dated 4-21-02 by and between the undersigned
("Lessee") and Citicorp Vendor Finance, Inc. ("Lessor"), Lessee hereby:

      (a) certifies and warrants to the Lessor that all the equipment (the
      "Equipment") described in the above referenced equipment schedule (the
      "Schedule") has been delivered, inspected, fully installed and is
      operational, and has not been previously used or placed in service for its
      specifically assigned function for the first time, unless otherwise
      expressly indicated on the Schedule, prior to the Acceptance Date as
      indicated below;

      (b) accepts all the Equipment for all purposes under the Lease and all
      attendant documents as of such Acceptance Date;

      (c) restates and reaffirms, as of such Acceptance Date, each of the
      representations, warranties and covenants given to Lessor in the Lease;

      (d) acknowledges and represents that it has reviewed and approves of all
      of the purchase documents for the Equipment, if any.

      (e) confirms that this acceptance and the Lease is irrevocable.

      ACCEPTANCE DATE:      6-10-02
                       -------------------

               Lessee: Virologic, Inc.

                       By:  /s/ KAREN WILSON
                          -------------------------

                       Name:    Karen Wilson
                            -----------------------

                       Title:   CFO
                             ----------------------

                               COUNTERPART 1 OF 1
<PAGE>
                                                          [CitiCapital(SM) LOGO]

                                                            DATE: APRIL 12, 2002

Re: Equipment Schedule No. 200062448 to Master Agreement No. 200062448 (the
"Agreement") between Virologic, Inc. as user ("User") and Citicorp Vendor
Finance, Inc., as owner ("Owner").

For good and valuable consideration, the receipt of which is hereby
acknowledged, and intending to be legally bound, the parties hereto agree as
follows:

1.   Provided no Event of Default exists uncured and notwithstanding anything
     contained in the Agreement to the contrary, Owner hereby grants to User the
     option to purchase the equipment subject to the Agreement (the "Equipment")
     at the end of the initial term of the Agreement for $1.00 (the "Purchase
     Option"). User shall exercise the Purchase Option by giving Owner not less
     than 30 days written notice prior to the last day of the initial term of
     the Agreement. IF THE PURCHASE OPTION IS EXERCISED, THE EQUIPMENT WILL BE
     SOLD BY OWNER TO USER "AS IS, WHERE IS", WITHOUT ANY WARRANTY, EXPRESS OR
     IMPLIED, INCLUDING WITHOUT LIMITATION ANY WARRANTY OF MERCHANTABILITY OR
     FITNESS FOR A PARTICULAR PURPOSE OR USE, OR WARRANTY OF TITLE.

2.   In the event that User does not elect to purchase the Equipment under the
     Purchases Option or the Purchase Option is deemed null and void under the
     circumstances described in Paragraph 1 herein, User shall return the
     Equipment in accordance with the terms and conditions of the Agreement.

3.   Capitalized terms used but not defined herein shall have the meanings
     ascribed to such terms in the Agreement.

4.   Except to the extent expressly modified by this letter agreement, the terms
     and conditions of the Agreement shall remain unchanged and in full force
     and effect.

Each of the parties hereto has caused this letter agreement to be executed by
its duly authorized officers, all as of the date first above written.

USER: VIROLOGIC, INC.                   CITICORP VENDOR FINANCE, INC.

BY:  /s/ Karen Wilson                   BY:  /s/ Bonnie Pszaegowski
     --------------------------              ------------------------------

TITLE:    CFO                           TITLE:    AM
      -------------------------               -----------------------------

DATE:     4/21/02                       DATE:     6-11-02
      -------------------------               -----------------------------

$1.00 Option Letter
Revised 5/01

CitiCapital is a service mark of Citicorp
<PAGE>

                 SECRETARY OR ASSISTANT SECRETARY'S CERTIFICATE

             AS TO CORPORATE RESOLUTION AND INCUMBENCY OF OFFICERS

         I HEREBY CERTIFY THAT I AM SECRETARY/(ASSISTANT SECRETARY) of

                                Virologic, Inc.
                             (Legal Name of Lessee)
and that the following is a true and correct copy of a resolution duly adopted
by the Board of Directors either by unanimous written consent dated _______, or
at a meeting called pursuant to proper notice and held on 16, at which time a
quorum was present and voting throughout. I further certify that this resolution
is in full force and effect, never having been revoked or modified;

     RESOLVED, that       William D. Young         , the       CEO            ;
                    -------------------------------      ---------------------
                      (Name of Authorized Officer           (Title of Officer)

          Karen Wilson                     , the              CFO
-------------------------------------------      ---------------------------;
  (Name of Authorized Officer)                         (Title of Officer)

                                           , the
-------------------------------------------      ---------------------------;
  (Name of Authorized Officer)                         (Title of Officer)

of this corporation are each hereby authorized and directed to execute and
deliver on behalf of this Corporation under its corporate seal which the
Secretary (Assistant Secretary) of this Corporation is authorized to affix and
attest, a Lease Agreement by and between this Corporation and CITICORP VENDOR
FINANCE, INC., substantially in the form attached hereto and hereby approved,
but with such changes, supplements, modifications and additions as each
aforesaid officer in his sole discretion deems appropriate; the execution and
delivery by such officers to be conclusive evidence of this approval thereof;
and such officers are further directed and authorized to execute and deliver
from time to time and as often as s/he deems necessary or desirable additional
Lease Agreements covering certain equipment to be employed in the business of
this corporation; and such officers are further authorized and directed to
execute all such ancillary and supporting documents and instruments, and to do
any and all other things as may to such officers seem necessary or advisable to
effectuate the full intent and purposes of this resolution and of the said Lease
Agreement(s) and other documents.

     The Undersigned further certifies that the following persons are duly
elected, qualified and acting officers, continuously holding the office
indicated opposite each of their names and that the signature appearing opposite
each of their name is the genuine signature of such person;

Name                     Office             Signature

William D. Young          CEO               /S/ WILLIAM D. YOUNG
-----------------------  -----------------  -----------------------------
Karen Wilson              CFO               LS/ KAREN WILSON
-----------------------  -----------------  -----------------------------

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

BY: /s/ KATHY L. HIBBS                       (Seal)
   ------------------------------------------
    Secretary           (Assistant Secretary)

 Kathy L. Hibbs                           DATED: 4-16-2002
---------------------------------------         ----------
(Print or Type Name of Above Signature)
(CORPORATE SEAL)<PAGE>
                                                                   EXHIBIT 10.2

                                    SUBLEASE

        THIS SUBLEASE ("Sublease"), dated June 1, 2002 (the "Commencement
Date"), is entered into by and between DIADEXUS, INC., a Delaware corporation
("Sublandlord"), and VIROLOGIC, INC. a Delaware corporation ("Subtenant").

                                    RECITALS

        A. Sublandlord, as successor-in-interest to Subtenant pursuant to an
Assignment and Assumption of Lease of even date herewith, 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 (i)
that certain First Amendment to Lease Agreement dated February ___, 2000 and
(ii) that certain Consent to Assignment and Modification of Lease of even date
herewith (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 13,630 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.

           (a) This Sublease shall commence upon the Commencement Date, provided
Sublandlord and Subtenant have theretofore obtained the Consent to Assignment
and Modification of Lease (the "Consent") signed by the Master Landlord in the
form of Exhibit C attached hereto, and shall expire on September 30, 2003,
unless sooner terminated pursuant to any provision hereof.

           (b) Subtenant shall have an option to extend the term hereof to
December 31, 2003 (i.e., for a period of three (3) months); provided that
Subtenant delivers notice of such exercise to Sublandlord on or before January
1, 2003 and provided, further, that Subtenant is not in default under this
Sublease at the time of exercise or at the commencement of the extension period.

<PAGE>

        3. POSSESSION. Subtenant acknowledges that it is in possession of the
Sublease Premises on the Commencement Date.

        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") in an amount equal to a pro-rata portion of the base rent
payable by Sublandlord under the Master Lease based on the square footage of the
Sublease Premises in proportion to the square footage of the entire Premises, as
follows:

<TABLE>
<S>                                    <C>               <C>
               June 2002:               $28,350.00        ($2.08/square foot)
               July 2002-June 2003:     $29,168.00        ($2.14/square foot)
               July 2003-Sept. 2003     $30,122.00        ($2.21/square foot)
</TABLE>

If, pursuant to Section 2(b) above, the term of this Sublease is extended to
December 31, 2003, Base Rent during such extended term shall be the same as set
forth above for the months July, 2003 through September, 2003.

               (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 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 2003, together with
any notices received by Sublandlord from Master Landlord with respect thereto.

               (iii) Payment of Rent. If the termination or expiration date of
this Sublease does not fall on the last day of a calendar month, Rent for such
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.

                                       2
<PAGE>

           (b) 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.

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

        5. SECURITY DEPOSIT. On or prior to the Commencement Date, Subtenant
shall deliver to Sublandlord the sum of Fifty Six Thousand Seven Hundred Dollars
and No/100 Dollars ($56, 700.00) 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.

        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

                                       3
<PAGE>

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, and (b) the amortization of the cost of
tenant improvements, if any, paid for by Subtenant in connection with the
assignment or subletting.

        7. CONDITION OF SUBLEASE PREMISES. 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, and without any obligation on the part of Sublandlord to modify,
improve or otherwise prepare the Sublease Premises for Subtenant's occupancy.

        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

                                       4
<PAGE>

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, 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.

        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:       diaDexus, Inc.
                                             343 Oyster Point Boulevard
                                             South San Francisco, CA  94080
                                             Attn:  Sharon Tetlow

                    TO SUBTENANT AT:         Virologic, Inc.
                                             345 Oyster Point Boulevard
                                             South San Francisco, CA  94080
                                             Attn:  Karen Wilson/Kathy Hibbs

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

                                       5
<PAGE>

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 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 with respect to any obligation arising after the Commencement Date 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 Commencement Date, Sublandlord's leasehold estate is not
encumbered by any deed of trust or mortgage financing.

                                       6
<PAGE>

            (d) Subtenant represents to Sublandlord that, immediately prior to
the Commencement Date, (i) the Master Lease was in full force and effect, (ii)
Subtenant was not in default under the Master Lease with respect to any
obligation arising before the Commencement Date and, to Subtenant's knowledge,
Master Landlord was not in default thereunder, (iii) the Master Lease attached
hereto is a full and complete copy of the Master Lease, and (iv) Subtenant's
leasehold estate under the Master Lease was not encumbered by any deed of trust
or mortgage financing.

            (e) 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 and until the Consent 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

                                       7
<PAGE>

Subtenant in accordance with the terms of a separate agreement between Subtenant
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 Virologic, 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") pursuant to which the third party would occupy such portion of
the Premises during the term of this Sublease, 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 during the
term of this Sublease.

            (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 an
amendment to this Sublease to incorporate the Offered Space. The parties shall
use best efforts to finalize and execute such sublease within ten (10) days of
Sublandlord's receipt of the Acceptance Notice. The amendment shall (i) add the
Offered Space to the Sublease Space, (ii) set forth the economic terms
applicable to the Offered Space, and (iii) provide that the term of the Offered
Space is coterminous with the Sublease Premises. Base Rent for the Offered Space
shall be the "Fair Market Rent" for the Offered Space as agreed to by the
parties. "Fair Market Rent" shall mean the then current market rent for
comparable facilities in the proximate South San Francisco market area. The
definition of comparable facilities shall incorporate the parking amenities of
the Premises and its use as an office/laboratory space, and the Building's
location, age, quality, amenities, identity, exterior appearance, interior
improvements, and type of construction. 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 (e) below. In no event, however, shall Base Rent for the Offered
Space be less than the then current Base Rent for the Sublease Premises.

            (d) 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.

            (e) If Sublandlord and Subtenant are unable to agree on Fair Market
Rent pursuant to subsection 19(c) above, then the parties shall submit the
matter to arbitration. The

                                       8
<PAGE>

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) 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. 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 "Term Commencement Date" of the Master
Lease, ordinary wear and tear excepted.

        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.

        22. 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.

        23. 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.

                                       9
<PAGE>

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

SUBLANDLORD:  DIADEXUS,  INC.,                SUBTENANT:  VIROLOGIC, INC.,

a Delaware corporation                        a Delaware corporation

By: /s/ Sharon Tetlow                         By: /s/ William D. Young
   ------------------------------                 -----------------------------
Print Name: Sharon Tetlow                     Print Name: William D. Young
            ---------------------                         ---------------------
Its: CFO                                      Its: Chairman & CEO
     ----------------------------                   ---------------------------

                                       10
<PAGE>

                                    EXHIBIT A

                                  MASTER LEASE

Office Lease by and between ViroLogic and Trammell Crow Northern California
Development, Inc. dated as of November 23, 1999 - Filed as an exhibit to the
Registrant's Registration Statement on Form S-1 (No. 333-30896) or amendments
thereto and incorporated herein by reference.

<PAGE>
                                  EXHIBIT A-1

                       FIRST AMENDMENT TO LEASE AGREEMENT

     THIS FIRST AMENDMENT TO LEASE AGREEMENT ("Amendment") is dated as of
February __, 2000, between ARE-Technology Center SSF, LLC, a Delaware limited
liability company ("Landlord"), and Virologic, Inc., a California corporation
("Tenant").

     A.   Trammell Crow Northern California Development, Inc. ("Original
Landlord") and Tenant entered into that certain Lease Agreement dated as of
November 23, 1999 (the "Lease"), with respect to certain premises to be located
at 335 Oyster Point Boulevard, South San Francisco, California (the "Premises").
Unless otherwise defined in this Amendment, initially-capitalized terms used
herein shall have the meanings set forth in the Lease.

     B.   Original Landlord has contracted to acquire the real property upon
which the Premises are to be located (the "Project"), and intends to assign its
rights to acquire the Project to Landlord.

     C.   In connection with the assignment of its rights to acquire the
Project, Original Landlord intends to assign all of its rights and interest
under the Lease to Landlord.

     D.   Landlord and Tenant wish to amend the Lease as set forth herein.

     NOW THEREFORE, in consideration of the foregoing Recitals, the mutual
covenants and agreements contained herein, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged,
Landlord and Tenant agree, and amend the Lease, as follows:

     1.   Effective Date.

     Landlord and Tenant agree that this Amendment shall be effective upon the
assignment of the Lease to Landlord by Original Landlord, and such assignment
shall be a condition precedent to the effectiveness of this Amendment. The date
upon which the assignment is made and this Amendment becomes effective shall be
called the "Effective Date".

     2.   Transportation Demand Management Program.

     The Lease is hereby amended to include the following provision:

          Landlord and Tenant acknowledge that in connection with the
          development of the Project, the Peninsula Congestion Relief Alliance,
          on behalf of the Inter-City and Multi-City TSM Agencies, San Mateo
          County, will propose a Transportation

<PAGE>
            Demand Management ("TDM") program which will focus on reducing
            traffic congestion in the vicinity of the Project. The parties
            further acknowledge that implementation of the TDM program is
            expected to be required by the City of South San Francisco as a
            condition of approval of the development of the Project. Tenant
            agrees to cooperate with Landlord in the implementation of the TDM
            program, to participate in the TDM program, and to pay Tenant's
            Proportionate Share of the costs related to the TDM program.

      3.    Counterparts.

      This Amendment may be executed in any number of counterparts, each of
which when so executed and delivered shall be deemed to be an original and all
of which counterparts taken together shall constitute but one and the same
instrument. Signature pages may be detached from the counterparts and attached
to a single copy of this Amendment to physically form one document.

      4.    Reaffirmation of Obligations.

      Tenant hereby acknowledges and reaffirms its obligations under the Lease,
as such Lease has been amended by this Amendment, and agrees that any reference
made in any other document to the Lease shall mean the Lease as amended
pursuant to this Amendment. Except as expressly provided herein, the Lease
remains unmodified and in full force and effect. Any breach by Tenant of this
Amendment, including any exhibit hereto, shall constitute a breach and default
by Tenant under the Lease.

      5.    Time of Essence.

      Time is of the essence with respect to each provision of this Agreement.

                                       2
<PAGE>
        IN WITNESS WHEREOF, Landlord and Tenant have caused this Amendment to be
duly executed and delivered as of the date first above written.

LANDLORD

ARE-Technology Center SSF, LLC,
a Delaware limited liability company

By: Alexandria Real Estate Equities, L.P.,
    a Delaware limited partnership
    its managing member

    By: ARE-QRS CORP.,
        a Maryland corporation,
        its general partner

        By: /s/ [SIGNATURE ILLEGIBLE]
           -----------------------------------
        Its:
            ----------------------------------

TENANT

VIROLOGIC, INC.,
a California corporation

By: /s/ [SIGNATURE ILLEGIBLE]
   ----------------------------------------
Its: President
    ---------------------------------------

                                       3

<PAGE>
                                                      CONFIDENTIAL & PROPRIETARY
                                                       DO NOT COPY OR DISTRIBUTE

                    ACKNOWLEDGMENT OF TERM COMMENCEMENT DATE

        This ACKNOWLEDGMENT OF TERM COMMENCEMENT DATE is made this 1st day of
November, 2001, between ARE-TECHNOLOGY CENTER SSF, LLC, a Delaware limited
liability company ("LANDLORD"), and VIROLOGIC, INC., a Delaware corporation
("TENANT"), and is attached to and made a part of that certain Lease dated
November 23, 1999, by and between Landlord's predecessor-in-interest, Trammell
Crow Northern California Development, Inc., and Tenant, as amended by that
certain First Amendment to Lease Agreement dated as of February __, 2000, by and
between Landlord and Tenant (as amended, the "LEASE"). Any initially capitalized
terms used but not defined herein shall have the meanings given them in the
Lease.

        Landlord and Tenant hereby acknowledge and agree for all purposes of the
Lease that the Term Commencement Date of the Lease is June 26, 2001. Tenant
further acknowledges that Tenant accepts the Premises.

        IN WITNESS WHEREOF, Landlord and Tenant have executed this
Acknowledgment of Term Commencement Date to be effective on the date first
above written.

        TENANT:

        VIROLOGIC, INC.,
        a Delaware corporation

        By: /s/ KAREN WILSON
           -------------------------------------
        Its: CFO
            ------------------------------------

        LANDLORD:

        ARE-TECHNOLOGY CENTER SSF, LLC,
        a Delaware limited liability company

        By: Alexandria Real Estate Equities, L.P.,
            a Delaware limited partnership,
            its managing member

            By: ARE-QRS CORP.,
                a Maryland corporation,
                its general partner

                By: /s/ [SIGNATURE ILLEGIBLE]
                   -------------------------------------
                Its: SENIOR VICE PRESIDENT,
                     BUSINESS DEVELOPMENT &
                     LEGAL AFFAIRS
                     -----------------------------------

<PAGE>
                                   Exhibit B

                               Sublease Premises

                                  First Floor
<PAGE>
                                   Exhibit B

                               Sublease Premises

                                   2nd Floor

<PAGE>
                                    EXHIBIT C

                               CONSENT TO SUBLEASE

                                [to be attached]

                                       13
<PAGE>

                                                                      EXHIBIT C

                 CONSENT TO ASSIGNMENT AND MODIFICATION OF LEASE

        This CONSENT TO ASSIGNMENT AND MODIFICATION OF LEASE (this "ASSIGNMENT
CONSENT"), effective as of June 1, 2002 (the "EFFECTIVE DATE"), is entered into
by (i) ARE-TECHNOLOGY CENTER SSF, LLC, a Delaware limited liability company
("LANDLORD"), (ii) VIROLOGIC, INC., a Delaware corporation ("CURRENT TENANT"),
and (iii) DIADEXUS, INC., a Delaware corporation ("NEW TENANT"), as follows:

                                    RECITALS

        A. Current Tenant currently leases the entire building located at 343
Oyster Point Boulevard in South San Francisco, California (the "PREMISES") from
Landlord pursuant to a certain Lease made as of November 23, 1999, between
Landlord's predecessor-in-interest, Trammell Crow Northern California
Development, Inc., and Current Tenant, as amended by a certain First Amendment
To Lease Agreement dated as of February ____, 2000, between Landlord and Current
Tenant (collectively, the "LEASE"). All initially capitalized terms not
expressly defined in this Assignment Consent shall have the meanings given to
such terms in the Lease unless the context clearly indicates otherwise.

        B. Current Tenant and New Tenant have entered into various agreements
pursuant to which, among other things, (i) Current Tenant is assigning to New
Tenant of all of Current Tenant's right, title, and interest in and to the Lease
(the "LEASEHOLD INTEREST"), and (ii) Current Tenant is selling and transferring
to New Tenant all of Current Tenant's ownership interest in and to all of the
Movable Equipment and Trade Fixtures described in Exhibit B-3 of the Lease,
excluding items 1 through 6 described in such Exhibit B-3 (collectively, the
"EQUIPMENT").

        C. New Tenant currently occupies 40,350 square feet of the Premises
pursuant to a certain Sublease dated May 17, 2001, between Current Tenant (as
sublandlord) and New Tenant (as subtenant) (the "CURRENT SUBLEASE"). In addition
to the transactions described in Recital B above (the "ASSIGNMENT
TRANSACTIONS"), (i) New Tenant is subleasing to Current Tenant 13,630 square
feet of space in the Premises, and (ii) Current Tenant and New Tenant are
terminating the Current Sublease. The agreements of Landlord, Current Tenant,
and New Tenant (each, a "PARTY" and collectively, the "PARTIES") regarding the
transactions described in this Recital (the "SUBLEASE TRANSACTIONS") are
contained in a certain Consent To Sublease of even date herewith (the "SUBLEASE
CONSENT").

        D. New Tenant and Current Tenant expressly acknowledge and agree that
the Assignment Transactions require Landlord's consent. In addition, New
Tenant's obligation to acquire and assume the Leasehold Interest is subject to
certain specific modifications of the terms, covenants, and conditions in the
Lease.

        NOW, THEREFORE, in consideration of the foregoing Recitals, which are
incorporated herein by this reference, the covenants in this Assignment Consent,
and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, the Parties hereby agree as follows:

        1. CONSENT TO ASSIGNMENT OF LEASE AND TRANSFER OF EQUIPMENT. Current
Tenant and New Tenant each hereby represents and warrants to Landlord that: (i)
attached to this Assignment Consent as Attachment 1 is a correct and complete
copy of the Assignment and Assumption of Lease (the "LEASEHOLD ASSIGNMENT")
pursuant to which Current Tenant is

<PAGE>
assigning to New Tenant, and New Tenant is assuming all of Current Tenant's
obligations in connection with, the Leasehold Interest; (ii) the effectiveness
of the Leasehold Assignment is not subject to any oral or written agreement
between Current Tenant and New Tenant that provides for a revocation,
rescission, cancellation, termination, or other nullification of the Leasehold
Assignment or for ownership of the Leasehold to revert to Current Tenant upon
the occurrence or failure to occur of any other event (including, but not
limited to, the failure to pay any required consideration for such Leasehold
Assignment); (iii) attached to this Assignment Consent as Attachment 2 is a
correct and complete copy of the Warranty Bill of Sale (the "BILL OF SALE")
pursuant to which Current Tenant is selling and transferring to New Tenant all
of Current Tenant's ownership interest in and to all of the Equipment, and (iv)
the effectiveness of the Bill of Sale is not subject to any oral or written
agreement between Current Tenant and New Tenant that provides for a revocation,
rescission, cancellation, termination, or other nullification of the Bill of
Sale, for ownership of the Equipment to revert to Current Tenant, or for Current
Tenant to have any lien or claim against any of the Equipment or the right to
re-possess any of the Equipment upon the occurrence or failure to occur of any
other event (including, but not limited to, the failure to pay any required
consideration for the Equipment). Landlord hereby consents to (x) Current
Tenant's assignment of the Leasehold Interest to New Tenant, in accordance with
the terms, covenants, and conditions in the Leasehold Assignment, and (y)
Current Tenant's sale and transfer to New Tenant of all of Current Tenant's
ownership interest in and to all of the Equipment, in accordance with the terms,
covenants, and conditions in the: Bill of Sale. Landlord neither approves nor
disapproves any of the terms, covenants, or conditions in the Lease Assignment
or in the Bill of Sale, which are and will remain matters solely between Current
Tenant and New Tenant.

        2. MODIFICATION OF LEASE. The terms, covenants, and conditions in the
Lease shall be updated, corrected, and/or modified as of the Effective Date as
follows:

           (a) BASIC LEASE INFORMATION:

               i) TENANT: diaDexus, Inc., a Delaware corporation;

               ii) TENANT'S ADDRESS: 343 Oyster Point Boulevard, South San
Francisco, California 94080, Attention: Ms. Sharon Tetlow;

               iii) LANDLORD: ARE-Technology Center SSF, LLC, a Delaware limited
liability company;

               iv) LANDLORD'S ADDRESS: For payments: 135 North Los Robles
Avenue, Suite 250, Pasadena, California 91101, Attention: Accounts Receivable.
For notices: 135 North Los Robles Avenue, Suite 250, Pasadena, California 91101,
Attention: Corporate Secretary;

               v) PROJECT: A two (2) building project totaling approximately
107,960 square feet on the land in South San Francisco, California legally
described in Exhibit A-1 attached hereto.

               vi) BUILDING: That approximately 53,980 square foot two (2) story
building within the Project known as 343 Oyster Point Boulevard, South San
Francisco, California 94080, as approximately depicted on the site plan attached
as Exhibit A-2; and

               vii) PREMISES: The Building known as 343 Oyster Point Boulevard,
South San Francisco, California 94080, as shown herein in Exhibit A-2.

                                       2
<PAGE>

           (b) PARAGRAPH 8.B.(3): The fifth (5th) sentence in Paragraph 8.B.(3)
of the Lease shall be deleted and the following substituted in its place: "In
any event, deductible amounts shall not exceed ten thousand dollars
($10,000.00)."

           (c) SECTION 37.C.: The second paragraph of Section 37.C. of the Lease
shall be deleted and the following substituted in its place: "The Base Rent for
the Premises under such option shall be the then current market rent for
comparable facilities in the proximate South San Francisco market area. The
definition of comparable facilities shall incorporate the parking amenities of
the Premises and its use as office/laboratory space, and the Building's
location, age, quality, amenities, identity, exterior appearance, interior
improvements, and type of construction, but shall not incorporate any continuing
liability of Tenant for Building shell upgrades. In no event shall Base Rent at
the commencement of the first option term be less than Base Rent for the last
month of the original Term (minus the $0.11 per square foot charge for Building
shell upgrades included in Base Rent during the original Term). In no event
shall Base Rent at the commencement of the second option term be less than Base
Rent for the last month of the first option term."

           (d) PARAGRAPH 21.A.: Notwithstanding the provisions of the last
sentence of Paragraph 21.A. of the Lease, the right to assign and/or sublet the
Premises shall inure to the benefit of New Tenant upon the assignment of the
Leasehold from Current Tenant to New Tenant and thereafter shall be personal to
New Tenant and any Permitted Assignee under the Lease; provided, however, that
this shall be a one-time forbearance by Landlord, shall not be construed as
having created a custom, practice, or manner contrary to the specific terms,
covenants, and conditions of the Lease or as having permanently modified the
same, and shall not be deemed a waiver of Landlord's right to enforce strictly
the terms of the last sentence of Paragraph 21.A. of the Lease at any time after
the Effective Date.

           (e) PARAGRAPH 21.F.: Notwithstanding the provisions of Paragraph
21.F. of the Lease, any options currently included in the Lease to renew or
expand shall not be terminated by the assignment of the Leasehold from Current
Tenant to New Tenant; provided, however, that this shall be a one-time
forbearance by Landlord, shall not be construed as having created a custom,
practice, or manner contrary to the specific terms, covenants, and conditions of
the Lease or as having permanently modified the same, and shall not be deemed a
waiver of Landlord's right to enforce strictly the terms of Paragraph 21.F. of
the Lease in the event of an assignment or subletting by the Tenant under the
Lease (except in connection with a Permitted Assignee) at any time after the
Effective Date.

Except to the extent expressly updated, corrected, and/or modified in this
Section 2, all of the terms, covenants, and conditions in the Lease shall remain
in full force and effect (including, without limitation, rent, renewal options,
and amount of security deposit). In the event, however, of any inconsistency or
conflict between the terms, covenants, and conditions in this Assignment Consent
and in the Lease, the terms, covenants, and conditions in this Assignment
Consent shall control. New Tenant hereby expressly acknowledges the following
provisions in the Lease: (x) the initial Term of the Lease commenced on June 26,
2001, and expires on June 30, 2011; (y) Base Rent due under the Lease as of June
1, 2002, is $112,278.40 per month (which includes $0.11 per square foot in
additional rent for Building shell upgrades) and will increase 3% on July 1,
2002, and on each July 1st thereafter during the initial Term of the Lease, in
accordance with the Base Rent Schedule in the Basic Lease Information and
Section 37.E. of the Lease, respectively; and (z) the Security Deposit under the
Lease is a cash deposit of $127,933.00 plus a Letter of Credit in the amount of
$400,000.00, which Letter of Credit must comply with the requirements set forth
in Section 19 of the Lease and is subject to reduction as set forth therein.

                                       3
<PAGE>

        3. MISCELLANEOUS PROVISIONS.

           (a) CONDITION OF PREMISES: All currently installed utility systems
and related infrastructure within the Premises (collectively, "INFRASTRUCTURE")
shall remain in their current location after the Effective Date. Landlord's
execution of this Assignment Consent, in and by itself, shall not constitute or
give rise to, and under no circumstances shall such execution, in and by itself,
be deemed, construed, or interpreted as constituting or giving rise to, any
representation or warranty by Landlord regarding the condition of any portion or
component of the Premises (including, without limitation, all currently
installed Infrastructure).

           (b) COMMISSIONS: Current Tenant shall be solely responsible and
liable for, and under no circumstances shall Landlord or New Tenant have any
responsibility or liability for, any commission, fee, or other payment (a
"COMMISSION") due to CRESA Partners in connection with the Assignment
Transactions. Current Tenant hereby indemnifies and agrees to protect, defend,
and hold Landlord and New Tenant harmless from and against any and all claims,
losses, damages, costs, and expenses (including reasonable attorneys' fees and
disbursements) that may be incurred by Landlord or New Tenant, respectively,
with respect to any Commissions payable in connection with the Assignment
Transactions that result from the actions of Current Tenant. New Tenant hereby
indemnifies and agrees to protect, defend, and hold Landlord and Current Tenant
harmless from and against any and all claims, losses, damages, costs, and
expenses (including reasonable attorneys' fees and disbursements) that may be
incurred by Landlord or Current Tenant, respectively, with respect to any
Commissions payable in connection with the Assignment Transactions that result
from the actions of New Tenant.

           (c) COUNTERPARTS: This Assignment Consent may be executed in any
number of counterparts, each of which shall be deemed an original and all of
which, taken together, shall constitute a single agreement with the same effect
as if all Parties had signed the same signature page. Any signature page from
any counterpart of this Assignment Consent, signed only by one Party, may be
detached from such counterpart and re-attached to any other counterpart of this
Assignment Consent that has a signature page signed only by one or both of the
other Parties.

           (d) NOTICES: All notices or other communications hereunder shall be
in writing and may be given personally, by reputable overnight delivery service
(including overnight U.S. mail), or by facsimile transmission (with in the case
of a facsimile transmission, confirmation by reputable overnight delivery
service) to the Parties at the following addresses:

If to Landlord:                              With a copy to:

c/o Alexandria Real Estate Equities, Inc.    McKay, Meyer and Herbert
135 N. Los Robles Ave., Suite 250            1801 Century Park East, 25th Floor
Pasadena, California 91101                   Los Angeles, California 90067-2327
Attention:       Corporate Secretary         Attention:     David S. Meyer, Esq.
Re:              343 Oyster Point            Re:            343 Oyster Point
Facsimile:       626-578-0770                Facsimile:     310-772-0239

                                       4
<PAGE>

If to New Tenant:                            With a copy to:

diaDexus, Inc.                               Latham & Watkins
343 Oyster Point Boulevard                   505 Montgomery Street, Suite 1900
South San Francisco, CA 94080                San Francisco, California 94111
Attention:      Ms. Sharon Tetlow            Attention:    Kenneth Whiting, Esq.
Re:             343 Oyster Point             Re:           diaDexus, Inc.
Facsimile:      650-246-6503                 Facsimile:    415-395-8095

If to Current Tenant:                        With a copy to:

Virologic, Inc.                              Virologic, Inc.
345 Oyster Point Boulevard                   345 Oyster Point Boulevard
South San Francisco, CA 94080                South San Francisco, CA 94080
Attention:      Ms. Karen Wilson             Attention:     Kathy Hibbs, Esq.
Re:             343 Oyster Point             Re:            343 Oyster Point
Facsimile:      650-635-1111                 Facsimile:     650-635-1111

           (e) AMENDMENTS; WAIVERS: No amendment, modification, supplement, or
waiver of this Assignment Consent shall be binding unless executed in writing by
the Party to be bound thereby. No waiver of any provision of this Assignment
Consent shall be deemed a waiver of any other provision of this Assignment
Consent (whether or not similar), nor shall such waiver be deemed a continuing
waiver unless otherwise expressly provided.

           (f) CONSTRUCTION: This Assignment Consent shall not be construed more
strictly against one Party than against any other Party merely by virtue of the
fact that this Assignment Consent may have been prepared by counsel for one of
the Parties. Further, no inferences are to be drawn, and no conclusions are to
be made, based on the fact that a particular provision contained in a draft of
this Assignment Consent is not included in the executed version of this
Assignment Consent, and no differences between drafts of this Assignment Consent
and the executed version of this Assignment Consent may be used as evidence of
the Parties' intended interpretation of any of the terms of this Assignment
Consent.

           (g) INTEGRATION: This Assignment Consent and the Sublease Consent
constitute the entire agreement among the Parties with respect to Landlord's
consent to the Assignment Transactions and to the Sublease Transactions and are
intended by the Parties to be the final expression and the complete and
exclusive statement of the terms of such agreement, and supersedes all prior
agreements, understandings, negotiations, and discussions of the Parties,
whether oral or written, and there are no other agreements, express or implied,
made by the Parties in connection with Landlord's consent to the Assignment
Transactions and to the Sublease Transactions, except as may be specifically set
forth in any documents delivered pursuant hereto or in connection herewith.

           (h) FURTHER ASSISTANCE: Each Party agrees to perform, execute, and/or
deliver or cause to be performed, executed, and/or delivered any further acts,
instruments, and assurances as may be reasonably required to accomplish the
purposes of this Assignment Consent.

                                       5
<PAGE>

           (i) SUCCESSORS AND ASSIGNS; THIRD PARTIES: All of the rights, duties,
benefits, liabilities, and obligations of the Parties under this Assignment
Consent shall inure to the benefit of, and be binding upon, their respective
successors and assigns. Nothing expressed or implied in this Assignment Consent
is intended or shall be construed to confer upon or give to any person or
entity, other than the Parties and their successors or assigns, any rights or
remedies under or by reason of this Assignment Consent.

        IN WITNESS WHEREOF, the Parties have executed this Assignment Consent
effective as of the Effective Date.

                            LANDLORD:

                            ARE-TECHNOLOGY CENTER SSF, LLC,
                            a Delaware limited liability company

                            By: ALEXANDRIA REAL ESTATE EQUITIES, L.P.,
                                a Delaware limited partnership, managing member

                                By: ARE-QRS CORP.,
                                    a Maryland corporation, general partner

                                    By: /s/ JIM RICHARDSON
                                        ---------------------------------------
                                    Print Name: Jim Richardson
                                                -------------------------------
                                    Print Title: President
                                                -------------------------------

                            CURRENT TENANT:

                            VIROLOGIC, INC., a Delaware corporation

                            By:
                                -----------------------------------------------
                            Print Name:
                                        ---------------------------------------
                            Print Title:
                                         --------------------------------------

                            NEW TENANT:

                            DIADEXUS, INC., a Delaware corporation

                            By:
                               ------------------------------------------------
                            Print Name:
                                        ---------------------------------------
                            Print Title:
                                         --------------------------------------

                                       6
<PAGE>

           (i) SUCCESSORS AND ASSIGNS; THIRD PARTIES: All of the rights, duties,
benefits, liabilities, and obligations of the Parties under this Assignment
Consent shall inure to the benefit of, and be binding upon, their respective
successors and assigns. Nothing expressed or implied in this Assignment Consent
is intended or shall be construed to confer upon or give to any person or
entity, other than the Parties and their successors or assigns, any rights or
remedies under or by reason of this Assignment Consent.

        IN WITNESS WHEREOF, the Parties have executed this Assignment Consent
effective as of the Effective Date.

                            LANDLORD:

                            ARE-TECHNOLOGY CENTER SSF, LLC,
                            a Delaware limited liability company

                            By: ALEXANDRIA REAL ESTATE EQUITIES, L.P.,
                                a Delaware limited partnership, managing member

                                By: ARE-QRS CORP.,
                                    a Maryland corporation, general partner

                                    By:
                                        ---------------------------------------
                                    Print Name:
                                                -------------------------------
                                    Print Title:
                                                -------------------------------

                            CURRENT TENANT:

                            VIROLOGIC, INC., a Delaware corporation

                            By: /s/ WILLIAM D. YOUNG
                                -----------------------------------------------
                            Print Name: William D. Young
                                        ---------------------------------------
                            Print Title: Chairman & CEO
                                         --------------------------------------

                            NEW TENANT:

                            DIADEXUS, INC., a Delaware corporation

                            By:
                               ------------------------------------------------
                            Print Name:
                                        ---------------------------------------
                            Print Title:
                                         --------------------------------------

                                       6
<PAGE>

           (i) SUCCESSORS AND ASSIGNS; THIRD PARTIES: All of the rights, duties,
benefits, liabilities, and obligations of the Parties under this Assignment
Consent shall inure to the benefit of, and be binding upon, their respective
successors and assigns. Nothing expressed or implied in this Assignment Consent
is intended or shall be construed to confer upon or give to any person or
entity, other than the Parties and their successors or assigns, any rights or
remedies under or by reason of this Assignment Consent.

        IN WITNESS WHEREOF, the Parties have executed this Assignment Consent
effective as of the Effective Date.

                            LANDLORD:

                            ARE-TECHNOLOGY CENTER SSF, LLC,
                            a Delaware limited liability company

                            By: ALEXANDRIA REAL ESTATE EQUITIES, L.P.,
                                a Delaware limited partnership, managing member

                                By: ARE-QRS CORP.,
                                    a Maryland corporation, general partner

                                    By:
                                        ---------------------------------------
                                    Print Name:
                                                -------------------------------
                                    Print Title:
                                                -------------------------------

                            CURRENT TENANT:

                            VIROLOGIC, INC., a Delaware corporation

                            By:
                                -----------------------------------------------
                            Print Name:
                                        ---------------------------------------
                            Print Title:
                                         --------------------------------------

                            NEW TENANT:

                            DIADEXUS, INC., a Delaware corporation

                            By: /s/ SHARON TETLOW
                               ------------------------------------------------
                            Print Name: Sharon Tetlow
                                        ---------------------------------------
                            Print Title: CFO
                                         --------------------------------------

                                       6

<PAGE>

                                  ATTACHMENT 1

                          COPY OF LEASEHOLD ASSIGNMENT

                            [See Following Page(s)]

                                       7

<PAGE>
                       ASSIGNMENT AND ASSUMPTION OF LEASE

        THIS ASSIGNMENT AND ASSUMPTION OF LEASE is made and entered into as of
June 1, 2002 (the "Effective Date"), by and between Virologic, Inc., a Delaware
corporation ("Assignor"), and diaDexus, Inc., a Delaware corporation
("Assignee").

                                    RECITALS

        A. ARE-Technology Center SSF, LLC, a Delaware limited liability company,
successor-in-interest to Trammell Crow Northern California Development, Inc., as
landlord ("Landlord"), and Assignor, as tenant, are parties to that certain
Lease (the "Original Lease") dated as of November 23, 1999, as amended by (i)
that certain First Amendment to Lease Agreement dated as of February __, 2000 by
and between Landlord and Tenant and (ii) Consent to Assignment and Modification
of Lease of even date herewith (collectively, the "Lease"), pursuant to which
Assignor leases certain premises consisting of approximately 53,980 square feet
in a building described in the Original Lease as being located at 335 Oyster
Point Boulevard, South San Francisco, California (the "Premises"), and more
particularly described in the Lease. Notwithstanding the description in the
Original Lease of the street address of the Premises as being 335 Oyster Point
Boulevard, South San Francisco, California, the actual street address of the
Premises is 343 Oyster Point Boulevard, South San Francisco, California.

        B. Effective as of the Effective Date, Assignor desires to assign,
transfer and convey all of its right, title and interest in and to, and all of
its obligations under, the Lease to Assignee, and Assignee desires to accept
such assignment and assume such obligations.

        C. On the Effective Date, Assignor will transfer its ownership interest
in all of the Movable Equipment and Trade Fixtures described in Exhibit B-3 to
the Lease (excluding items 1 through 6 described in such Exhibit B-3) (the
"Equipment"), to Assignee.

                                    AGREEMENT

        NOW, THEREFORE, in consideration of the mutual covenants and agreements
contained hereinafter and for other good and valuable consideration, the receipt
and sufficiency of which are hereby acknowledged, Assignor and Assignee hereby
agree as follows:

        1. Assignment and Assumption. Effective as of the Effective Date,
Assignor hereby assigns, transfers and conveys to Assignee all of its right,
title and interest in and to, and all of its obligations under, the Lease.
Effective as of the Effective Date, Assignee hereby expressly accepts such
assignment and assumes such obligations and agrees to perform and fulfill all
obligations and duties of Assignor arising under the Lease from and after the
Effective Date.

        2. Reciprocal Indemnity.

           (a) Assignor shall defend, protect, indemnify, and hold harmless
Assignee from and against any and all loss, liability, claim, action, damages,
costs and expenses (including reasonable attorneys' fees), directly or
indirectly arising from or out of any failure by

<PAGE>

Assignor to perform Assignor's obligations, or any breach of Assignor's
obligations, under the Lease prior to the Effective Date.

           (b) Assignee shall defend, protect, indemnify, and hold harmless
Assignor from and against any and all loss, liability, claim, action, damages,
costs and expenses (including reasonable attorneys' fees), directly or
indirectly arising from or out of any failure by Assignee to perform Assignee's
obligations, or any breach of Assignee's obligations, under the Lease from and
after the Effective Date.

        3. Payment of Consideration. As consideration for Assignor's assignment
of the Lease and transfer of the Equipment to Assignee, Assignee will pay to
Assignor a total of $5,000,000.00, of which $2,229,228.00 is consideration for
the assignment of the Lease and $2,770,772.00 is consideration for the transfer
of the Equipment, in accordance with the following payment schedule:

<TABLE>
<S>                                      <C>
        Effective Date:                  $   3,000,000.00
        September 27, 2002               $   1,000,000.00
        December 28, 2002                $   1,000,000.00
</TABLE>

        4. Letter of Credit and Security Deposit. On the Effective Date,
Assignee shall (a) post a letter of credit in favor of Landlord in the amount of
$400,000.00 (the amount currently required under the Lease), which letter of
credit will comply with the requirements set forth in Section 19 of the Lease
and will be subject to reduction on the terms and conditions set forth therein
and (b) deliver to Landlord the cash security deposit in the amount of
$127,933.00 required by the Lease.

                                       2
<PAGE>

        5. Successors and Assigns. This Assignment and Assumption of Lease shall
be binding upon, and inure to the benefit of, the parties hereto and their
respective legal representatives, successors and assigns.

        6. Governing Law. This Assignment and Assumption of Lease shall be
construed and enforced in accordance with the laws of the State of California.

        IN WITNESS WHEREOF, the parties hereto have executed this Assignment and
Assumption of Lease as of the day and year first above written.

        ASSIGNOR:          VIROLOGIC, INC., A DELAWARE CORPORATION

                           By: /s/ William D. Young
                               -----------------------------------
                           Name: William D. Young
                                 ---------------------------------
                           Title: Chairman & CEO
                                  --------------------------------

       ASSIGNEE:           DIADEXUS, INC., A DELAWARE CORPORATION

                           By: /s/ Sharon Tetlow
                               -----------------------------------
                           Name: Sharon Tetlow
                                 ---------------------------------
                           Title: CFO
                                  --------------------------------

                                       3
<PAGE>

                                  ATTACHMENT 2

                              COPY OF BILL OF SALE

                            [See Following Page(s)]

                                        8
<PAGE>

                              WARRANTY BILL OF SALE

        VIROLOGIC, INC. ("SELLER"), for good and valuable consideration to it
paid by or on behalf of DIADEXUS, INC. ("PURCHASER"), does hereby grant,
bargain, sell, transfer and deliver unto Purchaser, its successors and assigns,
all of Seller's right, title to and interest in the Equipment described on
Exhibit B-3 attached hereto, excluding items 1 through 6 described in such
Exhibit B-3.

        TO HAVE AND TO HOLD the same unto Purchaser, its successors and assigns,
forever.

        Seller hereby warrants that it is the lawful owner of the Equipment
described above and has good right to sell the same and that title to all such
Equipment is on the date hereof free and clear of all claims, liens and
encumbrances of any nature and that Seller will defend such title.

        IN WITNESS WHEREOF, Seller has caused this Warranty Bill of Sale to be
executed by its duly authorized officer on the 1st day of June, 2002.

                                                VIROLOGIC, INC.

                                                By: /s/ William D. Young
                                                    ---------------------------
                                                Name: William D. Young
                                                      -------------------------
                                                Title:  Chairman & CEO
                                                        -----------------------

<PAGE>

                              CONSENT TO SUBLEASE

This CONSENT TO SUBLEASE (this "SUBLEASE CONSENT"), effective as of June 1, 2002
(the "EFFECTIVE DATE"), is entered into by (i) ARE-TECHNOLOGY CENTER
SSF, LLC, a Delaware limited liability company ("LANDLORD"), (ii) VIROLOGIC,
INC., a Delaware corporation ("CURRENT TENANT"), and (iii) DIADEXUS, INC., a
Delaware corporation ("NEW TENANT"), as follows:

                                    RECITALS

        A. Current Tenant currently leases the entire building located at 343
Oyster Point Boulevard in South San Francisco, California (the "PREMISES") from
Landlord pursuant to a certain Lease made as of November 23, 1999, between
Landlord's predecessor-in-interest, Trammell Crow Northern California
Development, Inc., and Current Tenant, as amended by a certain First Amendment
To Lease Agreement dated as of February ___, 2000, between Landlord and Current
Tenant (collectively, the "LEASE"). All initially capitalized terms not
expressly defined in this Sublease Consent shall have the meanings given to such
terms in the Lease unless the context clearly indicates otherwise.

        B. Concurrently with this Sublease Consent, (i) Current Tenant is
assigning to New Tenant of all of Current Tenant's right, title, and interest in
and to the Lease, and (ii) Current Tenant is selling and transferring to New
Tenant all of Current Tenant's ownership interest in and to all of the Movable
Equipment and Trade Fixtures described in Exhibit B-3 of the Lease, excluding
items 1 through 6 described in such Exhibit B-3. The agreements of Landlord,
Current Tenant, and New Tenant (each, a "PARTY" and collectively, the "PARTIES")
regarding the transactions described in this Recital (the "ASSIGNMENT
TRANSACTIONS") are contained in a certain Consent To Assignment and Modification
of Lease of even date herewith (the "ASSIGNMENT CONSENT").

        C. New Tenant currently occupies 40,350 square feet of the Premises
pursuant to a certain Sublease dated May 17, 2001, between Current Tenant (as
sublandlord) and New Tenant (as subtenant) (the "CURRENT SUBLEASE"). Among other
things, Landlord consented to the Current Sublease pursuant to a certain Consent
To Sublease made as of May 17, 2001, among Landlord, Current Tenant, and New
Tenant ("CONSENT TO CURRENT SUBLEASE"). Current Tenant and New Tenant have
entered into various agreements pursuant to which, among other things, (i) New
Tenant is subleasing to Current Tenant 13,630 square feet of space in the
Premises until September 30, 2003, with an option to extend the term thereof
until December 31, 2003, and (ii) Current Tenant and New Tenant are terminating
the Current Sublease.

        D. New Tenant and Current Tenant expressly acknowledge and agree that
the transactions described in Recital C above (the "SUBLEASE TRANSACTIONS")
require Landlord's consent.

        NOW, THEREFORE, in consideration of the foregoing Recitals, which are
incorporated herein by this reference, the covenants in this Sublease Consent,
and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, the Parties hereby agree as follows:

<PAGE>

        1. CONSENT TO NEW SUBLEASE AND TERMINATION OF CURRENT SUBLEASE.

           (a) Current Tenant and New Tenant each hereby represents and warrants
to Landlord that: (i) attached to this Sublease Consent as Attachment 1 is a
correct and complete copy of the Sublease (the "NEW SUBLEASE") pursuant to which
New Tenant is subleasing to Current Tenant, and Current Tenant is subleasing
from New Tenant, the 13,630 square feet of space in the Premises occupied by
Current Tenant as of the day immediately prior to the Effective Date (the "NEW
SUBLEASE PREMISES"); (ii) the effectiveness of the New Sublease is not subject
to any oral or written agreement between Current Tenant and New Tenant that
provides for a revocation, rescission, cancellation, termination, or other
nullification of the New Sublease upon the occurrence or failure to occur of any
other event (other than a breach or default under such New Sublease); (iii)
attached to this Sublease Consent as Attachment 2 is a correct and complete copy
of the Sublease Termination Agreement (the "CURRENT SUBLEASE TERMINATION")
pursuant to which Current Tenant and New Tenant have terminated the Current
Sublease as of the Effective Date, and (iv) the effectiveness of the Current
Sublease Termination is not subject to any oral or written agreement between
Current Tenant and New Tenant that provides for a revocation, rescission,
cancellation, or other nullification of the Current Sublease Termination upon
the occurrence or failure to occur of any other event. Subject to paragraphs (b)
through (i) below, Landlord hereby consents to New Tenant's sublease of the New
Sublease Premises to Current Tenant, in accordance with the terms, covenants,
and conditions in the New Sublease. Subject to paragraph (k) below, Landlord
hereby consents to the termination of the Current Sublease, in accordance with
the terms, covenants, and conditions in the Current Sublease Termination.
Landlord neither approves nor disapproves any of the terms or conditions in the
New Sublease or in the Current Sublease Termination, which are and will remain
matters solely between Current Tenant and New Tenant.

           (b) The New Sublease shall be a sublease only and not an assignment
of the Lease with respect to the New Sublease Premises, and there shall be no
further subletting or assignment of any part of the Premises (including, without
limitation, the New Sublease Premises) except in strict accordance with the
terms, covenants, and conditions in the Lease. Further, any modification or
extension of the New Sublease without Landlord's prior written consent (which
consent may not be unreasonably withheld, conditioned, or delayed) shall be void
and of no force or effect.

           (c) All of the terms, covenants, and conditions in the New Sublease
shall be subordinate and subject to (i) all of the terms, covenants, and
conditions in the Lease, (ii) all superior ground leases, mortgages, deeds of
trust, and other liens now or hereafter placed against the real property of
which the Premises are a part and to all advances secured thereby and to all
renewals, modifications, consolidations, replacements, and extensions thereof,
and (iii) all matters of record and all laws, ordinances, and regulations now or
hereafter affecting the real property of which the Premises are a part.

           (d) Nothing contained in the New Sublease shall be construed to
modify, waive, impair, or affect in any way any of the terms, covenants, and
conditions in the Lease (including, without limitation, the obligation of the
Tenant under the Lease to obtain any required consents for any other or future
sublettings or assignments), to waive any current or future breach of the Lease,
to compromise any rights or remedies of Landlord under the Lease against any
person or entity liable for the performance thereof, or to enlarge or increase
Landlord's obligations or liabilities under the Lease (including, without
limitation, any liability to the sublessee under the New Sublease (the "NEW
SUBLESSEE") for any portion of the security deposit held by the sublessor under
the New Sublease (the "NEW SUBLESSOR")), it being expressly acknowledged and
agreed by the Parties that all of the terms, covenants, and

                                       2
<PAGE>

conditions in the Lease shall remain in full force and effect, notwithstanding
the New Sublease. Further, the Tenant under the Lease shall remain liable and
responsible for performing and complying with all of the terms, covenants, and
conditions in the Lease that are to be performed or complied with by such Tenant
for all of the Premises, including, without limitation, the New Sublease
Premises.

           (e) Current Tenant (in its capacity as the New Sublessee), for the
benefit of Landlord, hereby expressly assumes and agrees to be bound by, and to
perform and comply with, all of the obligations of the Tenant under the Lease
that are applicable to the New Sublease Premises.

           (f) Landlord and Current Tenant (in its capacity as the New
Sublessee) each hereby releases the other, and each hereby waives its rights of
recovery against the other, for direct or consequential losses or damages
arising out of or incident to any perils covered by property insurance carried
by such party to the extent of such insurance, and each hereby waives any right
of subrogation that otherwise might exist in or accrue to any person on account
thereof.

           (g) Any act or omission of the New Sublessee or of anyone claiming
under or through the New Sublessee that violates any of the terms, covenants, or
conditions of the Lease shall be deemed a violation of the Lease by the Tenant
under the Lease.

           (h) Current Tenant (in its capacity as the New Sublessee) hereby
agrees that, upon a default by the Tenant under the Lease, Landlord may proceed,
but shall not be required to proceed, directly against such Tenant without first
exhausting any other rights or remedies Landlord may have against any other
person or entity liable to Landlord for the same or against any other security
for the same. If Landlord gives the New Sublessee notice that the Tenant under
the Lease is in default under the Lease, the New Sublessee thereafter shall make
directly to Landlord all payments otherwise due the New Sublessor under the New
Sublease, which payments shall be received by Landlord without any liability to
the Tenant under the Lease except to credit such payments against amounts due
under the Lease.

           (i) New Tenant (in its capacity as the Tenant under the Lease and its
capacity as the New Sublessor) and Current Tenant (in its capacity as the New
Sublessee) each hereby acknowledges and agrees that if the Lease is terminated,
for any reason, Landlord shall have no liability, responsibility, or obligation
to the New Sublessee, and the New Sublease shall automatically terminate, except
as expressly provided below. If the Lease is terminated, for any reason, then,
so long as the New Sublessee is not in default under the New Sublease, the New
Sublease shall become a direct lease between Landlord and the New Sublessee,
Landlord shall not interfere with or disturb the New Sublessee's use,
possession, and enjoyment of the New Sublease Premises, and the New Sublessee
shall attorn to Landlord and recognize Landlord as the New Sublessor. If the New
Sublease becomes a direct lease between Landlord and the New Sublessee, Landlord
shall undertake the obligations of the New Sublessor from the date of the
termination of the Lease (the "LEASE TERMINATION DATE") through the expiration
or earlier termination of the New Sublease, but Landlord, in undertaking such
obligations, shall not (i) be liable for any rent or any security deposit paid
by the New Sublessee under the New Sublease, except to the extent actually
delivered to Landlord, (ii) be liable for any act, omission, or default of the
Tenant under the Lease or of the New Sublessor under the Sublease that arose
prior to the Lease Termination Date, (iii) be subject to any defenses or offsets
that the New Sublessee may have against the New Sublessor that arose prior to
the Lease Termination Date, (iv) be bound by any changes or modifications made
to the New Sublease prior to the Lease Termination Date without Landlord's
written consent, or (v) be liable for any matters provided in

                                       3
<PAGE>

Sections 17 or 18 of the New Sublease. Notwithstanding the termination of the
Lease, if the New Sublease becomes a direct lease between Landlord and the New
Sublessee, Landlord shall continue to perform, from the Lease Termination Date
through the expiration or earlier termination of the New Sublease, the
obligations of Landlord set forth in Paragraphs 8, 10, 24, and 28 of the Lease.

           (j) Under no circumstances shall the term of the New Sublease be
extended beyond December 31, 2003.

           (k) As consideration for Landlord's consent to the Current Sublease
Termination and agreement to forego the periodic bonus rent payments now payable
by Current Tenant to Landlord under the Consent To Current Sublease ("CURRENT
SUBLEASE BONUS RENT"), Current Tenant shall pay Landlord a total of $937,546.00
(the "CONSIDERATION"), of which $237,546.00 shall be consideration for the
Current Sublease Bonus Rent already owed to Landlord by Current Tenant and
$700,000.00 shall be consideration for Landlord's agreement to forego any other
Current Sublease Bonus Rent that would have come due under the Consent To
Current Sublease, in accordance with the following schedule:

<TABLE>
<CAPTION>
          Date                       Amount
        --------                 ------------
<S>                              <C>
        06/01/02                  $562,527.60
        09/27/02                  $187,509.20
        12/28/02                  $187,509.20
</TABLE>

The effectiveness of this Sublease Consent (and of the Assignment Consent) shall
not be subject to Current Tenant's payment of the Consideration to Landlord, and
Landlord shall have no right to revoke, rescind, cancel, terminate, or otherwise
nullify this Sublease Consent (or the Assignment Consent) if Current Tenant
fails to pay to Landlord any part of the Consideration. Landlord's remedy in
such an event shall be to pursue its rights and/or remedies against Current
Tenant at law or in equity and/or to seek to recover from Current Tenant any
unpaid portion of the Consideration plus any actual or consequential damages
suffered by Landlord (including, without limitation, reasonable attorneys' fees
and disbursements) as a result of Current Tenant's breach.

        2. MISCELLANEOUS PROVISIONS.

           (a) CONDITION OF NEW SUBLEASE PREMISES: Prior to the Effective Date,
Current Tenant has been in possession of, and conducting business in, the New
Sublease Premises. Accordingly, (i) Current Tenant hereby expressly
acknowledges, for the benefit of Landlord, that Current Tenant has accepted the
New Sublease Premises in their "as-is" condition, without any qualifications,
restrictions, or limitations, and (ii) all currently installed utility systems
and related infrastructure within the Sublease Premises (collectively,
"INFRASTRUCTURE") shall remain in their current location after the Effective
Date. Landlord's execution of this Sublease Consent, in and by itself, shall not
constitute or give rise to, and under no circumstances shall such execution, in
and by itself, be deemed, construed, or interpreted as constituting or giving
rise to, any representation or warranty by Landlord regarding the condition of
any portion or component of the New Sublease Premises (including, without
limitation, all currently installed Infrastructure).

                                       4
<PAGE>

           (b) COMMISSIONS: Current Tenant shall be solely responsible and
liable for, and under no circumstances shall Landlord or New Tenant have any
responsibility or liability for, any commission, fee, or other payment (a
"COMMISSION") due to CRESA Partners in connection with the Sublease
Transactions. Current Tenant hereby indemnifies and agrees to protect, defend,
and hold Landlord and New Tenant harmless from and against any and all claims,
losses, damages, costs, and expenses (including reasonable attorneys' fees and
disbursements) that may be incurred by Landlord or New Tenant, respectively,
with respect to any Commissions payable in connection with the Sublease
Transactions that result from the actions of Current Tenant. New Tenant hereby
indemnifies and agrees to protect, defend, and hold Landlord and Current Tenant
harmless from and against any and all claims, losses, damages, costs, and
expenses (including reasonable attorneys' fees and disbursements) that may be
incurred by Landlord or Current Tenant, respectively, with respect to any
Commissions payable in connection with the Sublease Transactions that result
from the actions of New Tenant.

           (c) COUNTERPARTS: This Sublease Consent may be executed in any number
of counterparts, each of which shall be deemed an original and all of which,
taken together, shall constitute a single agreement with the same effect as if
all Parties had signed the same signature page. Any signature page from any
counterpart of this Sublease Consent, signed only by one Party, may be detached
from such counterpart and re-attached to any other counterpart of this Sublease
Consent that has a signature page signed only by one or both of the other
Parties.

           (d) NOTICES: All notices or other communications hereunder shall be
in writing and may be given personally, by reputable overnight delivery service
(including overnight U.S. mail), or by facsimile transmission (with in the case
of a facsimile transmission, confirmation by reputable overnight delivery
service) to the Parties at the following addresses:

If to Landlord:                               With a copy to:

c/o Alexandria Real Estate Equities, Inc.     McKay, Meyer and Herbert
135 N. Los Robles Ave., Suite 250             1801 Century Park East, 25th Floor
Pasadena, California 91101                    Los Angeles, California 90067-2327
Attention:   Corporate Secretary              Attention: David S. Meyer, Esq.
Re:          343 Oyster Point                 Re:        343 Oyster Point
Facsimile:   626-578-0770                     Facsimile: 310-772-0239

If to New Tenant:                             With a copy to:

diaDexus, Inc.                                Latham & Watkins
343 Oyster Point Boulevard                    505 Montgomery Street, Suite 1900
South San Francisco, CA 94080                 San Francisco, California 94111
Attention: Ms. Sharon Tetlow                  Attention:   Kenneth Whiting, Esq.
Re:        Virologic, Inc.                    Re:          diaDexus, Inc.
Facsimile: 650-246-6503                       Facsimile:   415-395-8095

                                        5
<PAGE>

If to Current Tenant:                         With a copy to:

Virologic, Inc.                               Virologic, Inc.
345 Oyster Point Boulevard                    345 Oyster Point Boulevard
South San Francisco, CA 94080                 South San Francisco, CA 94080
Attention:      Ms. Karen Wilson              Attention:     Kathy Hibbs, Esq.
Re:             343 Oyster Point              Re:            Virologic, Inc.
Facsimile:      650-635-1111                  Facsimile:     650-635-1111

           (e) AMENDMENTS; WAIVERS: No amendment, modification, supplement, or
waiver of this Sublease Consent shall be binding unless executed in writing by
the Party to be bound thereby. No waiver of any provision of this Sublease
Consent shall be deemed a waiver of any other provision of this Sublease Consent
(whether or not similar), nor shall such waiver be deemed a continuing waiver
unless otherwise expressly provided.

           (f) CONSTRUCTION: This Sublease Consent shall not be construed more
strictly against one Party than against any other Party merely by virtue of the
fact that this Sublease Consent may have been prepared by counsel for one of the
Parties. Further, no inferences are to be drawn, and no conclusions are to be
made, based on the fact that a particular provision contained in a draft of this
Sublease Consent is not included in the executed version of this Sublease
Consent, and no differences between drafts of this Sublease Consent and the
executed version of this Sublease Consent may be used as evidence of the
Parties' intended interpretation of any of the terms of this Sublease Consent.

           (g) INTEGRATION: This Sublease Consent and the Assignment Consent
constitute the entire agreement among the Parties with respect to Landlord's
consent to the Sublease Transactions and the Assignment Transactions and is
intended by the Parties to be the final expression and the complete and
exclusive statement of the terms of such agreement, and supersedes all prior
agreements, understandings, negotiations, and discussions of the Parties,
whether oral or written, and there are no other agreements, express or implied,
made by the Parties in connection with Landlord's consent to the Sublease
Transactions and the Assignment Transactions, except as may be specifically set
forth in any documents delivered pursuant hereto or in connection herewith.

           (h) FURTHER ASSISTANCE: Each Party agrees to perform, execute, and/or
deliver or cause to be performed, executed, and/or delivered any further acts,
instruments, and assurances as may be reasonably required to accomplish the
purposes of this Sublease Consent.

                                       6
<PAGE>

           (i) SUCCESSORS AND ASSIGNS; THIRD PARTIES: All of the rights, duties,
benefits, liabilities, and obligations of the Parties under this Sublease
Consent shall inure to the benefit of, and be binding upon, their respective
successors and assigns. Nothing expressed or implied in this Sublease Consent is
intended or shall be construed to confer upon or give to any person or entity,
other than the Parties and their successors or assigns, any rights or remedies
under or by reason of this Sublease Consent.

        IN WITNESS WHEREOF, the Parties have executed this Sublease Consent
effective as of the Effective Date.

                            LANDLORD:

                            ARE-TECHNOLOGY CENTER SSF, LLC,
                            a Delaware limited liability company

                            By: ALEXANDRIA REAL ESTATE EQUITIES, L.P.,
                                a Delaware limited partnership, managing member

                                By: ARE-QRS CORP.,
                                    a Maryland corporation, general partner

                                    By: /s/ JIM RICHARDSON
                                        ---------------------------------------
                                    Print Name: Jim Richardson
                                                -------------------------------
                                    Print Title: President
                                                 ------------------------------

                            CURRENT TENANT:

                            VIROLOGIC, INC., a Delaware corporation

                            By:
                               ------------------------------------------------
                            Print Name:
                                        ---------------------------------------
                            Print Title:
                                         --------------------------------------

                            NEW TENANT:

                            DIADEXUS, INC., a Delaware corporation

                            By:
                               ------------------------------------------------
                            Print Name:
                                        ---------------------------------------
                            Print Title:
                                         --------------------------------------

                                       7
<PAGE>

           (i) SUCCESSORS AND ASSIGNS; THIRD PARTIES: All of the rights,
duties, benefits, liabilities, and obligations of the Parties under this
Sublease Consent shall inure to the benefit of, and be binding upon, their
respective successors and assigns. Nothing expressed or implied in this Sublease
Consent is intended or shall be construed to confer upon or give to any person
or entity, other than the Parties and their successors or assigns, any rights or
remedies under or by reason of this Sublease Consent.

        IN WITNESS WHEREOF, the Parties have executed this Sublease Consent
effective as of the Effective Date.

                            LANDLORD:

                            ARE-TECHNOLOGY CENTER SSF, LLC,
                            a Delaware limited liability company

                            By: ALEXANDRIA REAL ESTATE EQUITIES, L.P.,
                                a Delaware limited partnership, managing member

                                By: ARE-QRS CORP.,
                                    a Maryland corporation, general partner

                                    By:
                                        ---------------------------------------
                                    Print Name:
                                                -------------------------------
                                    Print Title:
                                                -------------------------------

                            CURRENT TENANT:

                            VIROLOGIC, INC., a Delaware corporation

                            By: /s/ WILLIAM D. YOUNG
                                -----------------------------------------------
                            Print Name: William D. Young
                                        ---------------------------------------
                            Print Title: Chairman & CEO
                                         --------------------------------------

                            NEW TENANT:

                            DIADEXUS, INC., a Delaware corporation

                            By:
                               ------------------------------------------------
                            Print Name:
                                        ---------------------------------------
                            Print Title:
                                         --------------------------------------

                                       7
<PAGE>

           (i) SUCCESSORS AND ASSIGNS; THIRD PARTIES: All of the rights, duties,
benefits, liabilities, and obligations of the Parties under this Sublease
Consent shall inure to the benefit of, and be binding upon, their respective
successors and assigns. Nothing expressed or implied in this Sublease Consent is
intended or shall be construed to confer upon or give to any person or entity,
other than the Parties and their successors or assigns, any rights or remedies
under or by reason of this Sublease Consent.

        IN WITNESS WHEREOF, the Parties have executed this Sublease Consent
effective as of the Effective Date.

                            LANDLORD:

                            ARE-TECHNOLOGY CENTER SSF, LLC,
                            a Delaware limited liability company

                            By: ALEXANDRIA REAL ESTATE EQUITIES, L.P.,
                                a Delaware limited partnership, managing member

                                By: ARE-QRS CORP.,
                                    a Maryland corporation, general partner

                                    By:
                                        ---------------------------------------
                                    Print Name:
                                                -------------------------------
                                    Print Title:
                                                -------------------------------

                            CURRENT TENANT:

                            VIROLOGIC, INC., a Delaware corporation

                                    By:
                                        ---------------------------------------
                                    Print Name:
                                                -------------------------------
                                    Print Title:
                                                -------------------------------

                            NEW TENANT:

                            DIADEXUS, INC., a Delaware corporation

                            By: /s/ SHARON TETLOW
                                -----------------------------------------------
                            Print Name: Sharon Tetlow
                                        ---------------------------------------
                            Print Title: CFO
                                         --------------------------------------

                                       8

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