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                                                                  EXHIBIT 10.21

                         AMENDED AND RESTATED SUBLEASE

     THIS AMENDED AND RESTATED SUBLEASE (this "Sublease") is dated as of July
17, 2000, and is made by and between Senomyx, Inc., a Delaware corporation, as
successor in interest to Sequana Therapeutics, Inc. (dba Axys Pharmaceuticals,
Inc.) ("Sublessor"), and Akkadix Corporation, a California corporation, as
successor in interest to Xyris, Inc. ("Sublessee"). Sublessor and Sublessee
hereby agree as follows:

     1.   RECITALS: This Sublease is made with reference to the fact that
AREE-11099 North Torrey Pines, LLC, a Delaware Limited Liability Company,
successor in interest to Alexandria Real Estate Equities, Inc., formerly known
as Health Science Properties, Inc., a Maryland corporation as landlord ("Master
Lessor"), and Sublessor, as successor in interest to Sequana Therapeutics,
entered into that certain lease, dated as of November 20, 1995, as amended by a
letter agreement dated November 20, 1995, a First Amendment to Expansion Lease
dated October 1996, a Second Amendment to Expansion Lease dated May, 1997, and a
Third Amendment to Expansion Lease dated August 24, 1998 (the "Master Lease"),
with respect to premises consisting of approximately 60,056 rentable square feet
of space located at 11099 North Torrey Pines Road, La Jolla, California (the
"Demised Premises"). A copy of the Master Lease is attached hereto as Exhibit A.

     2.   PREMISES: In accordance with the terms of this Sublease, Sublessor
hereby subleases to Sublessee and Sublessee hereby subleases from Sublessor, a
portion of the Demised Premises as further described below (collectively, the
"Subleased Premises"):

(a)  Suite 250, consisting of approximately 2,981 rentable square feet, ("Suite
250");

(b)  Office 129, Office 130, Office 134, Office 135, and Office 136, consisting
of approximately 876.4 rentable square feet in the aggregate (collectively,
"Space I");

(c)  Office 131, Office 132, Office 133, and Office 137, consisting of
approximately 669.2 rentable square feet in the aggregate (collectively, "Space
II");

(d)  Office 138, consisting of approximately 202.9 rentable square feet ("Space
III");

(e)  Labs 38-40, consisting of approximately 1,277 rentable square feet of Suite
160 in the aggregate ("Labs 38-40").

(f)  Suite 220, consisting of approximately 4,403 rentable square feet ("Suite
220");

(g)  Suite 200 and Rooms 139, 140, 141, and 142, consisting of approximately
7,262.5 rentable square feet in the aggregate (collectively "Additional Space
I");

(h)  Rooms 46 and 47 on the first floor consisting of approximately 821 rentable
square feet in the aggregate (collectively "Additional Space II"); and


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(i)  Suite 290 consisting of approximately 6,750 rentable square feet
("Additional Space III").

The Subleased Premises are more particularly described on Exhibit B attached
hereto and incorporated herein.

     3.   TERM:

(a)  The term of this Sublease with respect to Suite 250 (the "Suite 250 Term")
shall commence on the later of (i) April 1, 1999, or (ii) the date two (2) days
after Sublessor's physical mapping group vacates Suite 250;

(b)  The term of this Sublease with respect to Space I (the "Space I Term")
shall commence on April 1, 1999;

(c)  The term of this Sublease with respect to Space II (the "Space II Term")
shall commence on the later of (i) May 1, 1999, or (ii) the date two (2) days
after the PPGx, Inc. personnel vacate Space II;

(d)  The term of this Sublease with respect to Space III (the "Space III Term")
shall commence on the later of (i) June 1, 1999, or (ii) the date two (2) days
after the Sublessor's personnel vacate Space III;

(e)  The term of this Sublease with respect to Labs 38-40 (the "Labs 38-40
Term") shall commence on the later of (i) May 1, 1999, or (ii) the date two (2)
days after PPGx, Inc. personnel vacates Labs 38-40, and shall terminate at the
close of business on February 7, 2000;

(f)  The term of this Sublease with respect to Suite 220 (the "Suite 220 Term")
Shall commence on August 1, 1999;

(g)  The term of this Sublease with respect to Additional Space I (the
"Additional Space I Term") shall commence on November 8, 1999;

(h)  The term of this Sublease with respect to Additional Space II (the
"Additional Space II Term") shall commence on February 8, 2000; and

(i)  The term of this Sublease with respect to Additional Space III shall
commence on July 17, 2000 and shall terminate on the close of business June 30,
2001. If, after January 1, 2001, Sublessee desires to terminate this Sublease
with respect to Additional Space III then sixty (60) days prior notice must be
given to Sublessor.

The commencement dates set forth in Section 3 (a) through (i) above, shall be
defined, collectively, as the "Commencement Dates."


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The term in each case set forth in Section 3 (a) through (h) above, shall
terminate on the earliest to occur of (a) the date which is five (5) days prior
to the expiration date of the Master Lease as provided in Section 2.1.7(b) of
the Master Lease (the "Expiration Date"), or (b) the date this Sublease is
terminated pursuant to its terms, or (c) the date the Master Lease is terminated
pursuant to its terms; or (d) thirty (30) days after Sublessor's receipt of
written notice from Sublessee, which written notice may be given by Sublessee at
any time on or after March 30, 2000.

     4.   RENT:

          A.   BASE RENT. Sublessee shall pay to Sublessor as the base rent for
each month during (a) the Suite 250 Term, the amount of Five Thousand Six
Hundred Ninety-Nine and 67/100 Dollars ($5,699.67) per month; (b) the Space I
Term, the amount of One Thousand Six Hundred Seventy-Five and 68/100 Dollars
($1,675.68) per month; (c) the Space II Term, the amount of One Thousand Two
Hundred Seventy-Nine and 51/100 Dollars ($1,279.51) per month; (d) the Space III
Term, the amount of Three Hundred Eighty-Seven and 94/100 Dollars ($387.94) per
month; (e) the Labs 38-40 Term, the amount of Two Thousand Four Hundred
Forty-One and 62/100 Dollars ($2,441.62) per month; (f) the Suite 220 Term, the
amount of Eight Thousand Four Hundred Eighteen and 54/100 Dollars ($8,418.54)
per month; (g) the Additional Space I Term, the amount of Thirteen Thousand
Eight Hundred Eighty-Six and 00/100 Dollars ($13,886) per month; (h) the
Additional Space II Term, the amount of One Thousand Five Hundred Seventy and
00/100 Dollars ($1,570) per month; and (i) the Additional Space III Term, the
amount of Fifteen Thousand One Hundred Eighty-Seven and 50/100 Dollars
($15,187.50) (collectively, "Base Rent"), subject to the rental adjustment
described below. Base Rent under this Sublease shall be adjusted on January 1 of
each year to equal the Base Rent then payable by Sublessor under the Master
Lease with respect to the Subleased Premises pursuant to Section 2.1.5, as
adjusted by Section 6 of the Master Lease. Notwithstanding the foregoing, in the
event Master Lessor refunds or abates any of the Rent (as defined in Section 4
(B) below) with respect to the Subleased Premises under the Master Lease,
Sublessor shall refund or abate Rent under this Sublease to the extent so
refunded or abated by Master Lessor. Base Rent and Additional Rent as defined in
Paragraph 4.B below, shall be paid on or before the first (1st) day of each
month. Base Rent and Additional Rent for any period during the Term hereof which
is for less than one (1) month of the Term shall be a pro rata portion of the
monthly installment based on the actual number of days in such month. Base Rent
and Additional Rent shall be payable without notice or demand and without any
deduction, offset, or abatement, in lawful money of the United States of
America. Base Rent and Additional Rent shall be paid directly to Sublessor at
its address set forth on the signature page, Attention: Accounts Receivable, or
such other address as may be designated in writing by Sublessor.

     B.   ADDITIONAL RENT. All monies other than Base Rent required to be paid
by Sublessee under this Sublease, including, without limitation any amounts
payable by Sublessor to the Master Lessor with respect to the Subleased Premises
as "Operating Expenses" (as defined in Section 7 of the Master Lease), shall be
deemed additional rent ("Additional Rent"). Base Rent and Additional Rent
hereinafter collectively shall be referred


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to as "Rent". Sublessee and Sublessor agree, as a material part of the
consideration given by Sublessee to Sublessor for this Sublease, that Sublessee
shall pay all costs, expenses, taxes, insurance, maintenance and other charges
of every kind and nature arising during the Term in connection with the
Subleased Premises such that Sublessor shall receive, as a net consideration for
this Sublease, the Base Rent payable under Paragraph 4.A hereof.

     5.   HOLDOVER: In the event that Sublessee does not surrender the Subleased
Premises by the Expiration Date in accordance with the terms of this Sublease,
Sublessee shall indemnify, protect, defend and hold harmless Sublessor from and
against all losses, costs, liabilities and damages resulting from Sublessee's
delay in surrendering the Subleased Premises and pay Sublessor holdover rent as
provided in Section 12 of the Master Lease.

     6.   REPAIRS: The parties acknowledge and agree that Sublessee is
subleasing the Subleased Premises on an "as is" basis, and that Sublessor has
made no representations or warranties with respect to the condition of the
Subleased Premises as of the Commencement Date except as set forth in this
paragraph. Sublessor shall have no obligation whatsoever to make or pay the cost
of any alterations, improvements or repairs to the Subleased Premises,
including, without limitation, any improvement or repair required to comply with
any law, regulation, building code or ordinance (including the Americans with
Disabilities Act of 1990). Sublessee shall inform Sublessor of any repairs that
are required to be performed by Master Lessor under the terms of the Master
Lease and Sublessor shall in turn promptly inform Master Lessor of such repairs
which shall remain Master Lessor's sole responsibility.

     7.   ASSIGNMENT AND SUBLETTING: Sublessee may not assign this Sublease,
sublet the Subleased Premises, transfer any interest of Sublessee therein or
permit any use of the Subleased Premises by another party, except in strict
accordance with Section 25 of the Master Lease, as incorporated herein.

     8.   ATTORNMENT: In the event Master Lessor gives Sublessee notice that
Sublessor is in default under the Master Lease, Sublessee shall thereafter make
all payments otherwise due Sublessor under this Sublease directly to Master
Lessor, which payments will be received by Master Lessor without any liability
on Master Lessor except to credit such payment against those due under the
Master Lease. Sublessor hereby agrees that Sublessee may rely on any such notice
by Master Lessor, and Sublessee shall have no duty of inquiry with respect to
the validity of the notice. Sublessee shall attorn to Master Lessor or its
successors and assigns should the Master Lease be terminated for any reason;
provided, however, that in no event shall Master Lessor or its successors or
assigns be obligated to accept such attornment.

     9.   USE: Sublessee may use the Subleased Premises only for wet laboratory
biotechnology research, and office uses. Sublessee shall not use, store,
transport or dispose of any hazardous material in or about the Subleased
Premises except in strict accordance with the provisions of Section 41 of the
Master Lease, as incorporated herein. Upon execution of this Sublease, Sublessee
shall deliver to Sublessor for Sublessor's


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approval a list of all hazardous materials Sublessee plans to use in the
Subleased Premises. Sublessee shall comply with all reasonable rules and
regulations promulgated from time to time by Sublessor and Master Lessor.
Sublessor shall use reasonable efforts to cause Master Lessor to provide, at
Sublessee's sole cost and expense, signage on the door of the Subleased Premises
and the building directory tablet that is reasonably acceptable to Sublessee,
Sublessor and Master Lessor.

     10.  DELIVERY AND ACCEPTANCE: By taking possession of the Subleased
Premises, Sublessee conclusively shall be deemed to have accepted the Subleased
Premises in their as-is, then-existing condition, without any warranty
whatsoever of Sublessor with respect thereto.

     11.  IMPROVEMENTS: No alteration or improvements shall be made to the
Subleased Premises, except in strict accordance with the provisions of Section
17 of the Master Lease, as incorporated herein. Any alterations or improvements
to the Subleased Premises shall be at Sublessee's sole cost and expense.
Sublessor shall have no obligation whatsoever to make any alterations or
improvements to the Subleased Premises.

     12.  RELEASE AND WAIVER OF SUBROGATION: Sublessor and Sublessee hereby
release each other to the extent provided in Section 21.7 of the Master Lease,
as incorporated herein. Each party shall use its best efforts to cause each
insurance policy obtained by it to provide that the insurer waives all right of
recovery against the other party and its agents and employees in connection with
any damage or injury covered by the policy, and each party shall notify the
other party if it is unable to obtain a waiver of subrogation.

     13.  INSURANCE: Sublessee shall obtain and keep in full force and effect,
at Sublessee's sole cost and expense, during the Term, the insurance required to
be carried by Sublessor, as tenant, under Section 21 of the Master Lease as
incorporated herein.

     14.  DEFAULT: Sublessee shall be in material default of its obligations
under this Sublease if any of the following events occur:

          A.   Sublessee fails to pay any Rent when due, when such failure
continues for three (3) days after written notice from Sublessor to Sublessee
that any such sum is due; or

          B.   Sublessee fails to perform any term, covenant or condition of
this Sublease (except those requiring payment of Rent) and fails to cure such
breach within ten (10) days after delivery of a written notice specifying the
nature of the breach; provided, however, that if more than ten (10) days
reasonably are required to remedy the failure, then Sublessee shall not be in
default if Sublessee commences the cure within the ten (10) day period and
thereafter completes the cure within thirty (30) days after the date of the
notice; or


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          C.   Sublessee commits any other act or omission which constitutes an
event of default under the Master Lease.

     15.  BROKER: Sublessor and Sublessee each represent to the other that they
have dealt with no real estate brokers, finders, agents or salesmen in
connection with this transaction. Each party agrees to hold the other party
harmless from and against all claims for brokerage commissions, finder's fees or
other compensation made by any other agent, broker, salesman or finder as a
consequence of said party's actions or dealings with such agent, broker,
salesman, or finder.

     16.  NOTICES: Unless at least five (5) days' prior written notice is given
in the manner set forth in this paragraph, the address of each party for all
purposes connected with this Sublease shall be that address set forth below
their signatures at the end of this Sublease. All notices, demands or
communications in connection with this Sublease shall be (a) personally
delivered; or (b) properly addressed and (i) submitted to an overnight courier
sendee charges prepaid, or (ii) deposited in the mail (registered or certified,
return receipt requested, and postage prepaid). Notices shall be deemed
delivered upon receipt, if personally delivered, one (1) business day after
being submitted to an overnight courier service and three (3) business days
after mailing, if mailed or submitted as set forth above. All notices given to
Master Lessor under the Master Lease shall be considered received only when
delivered in accordance with the Master Lease.

     17.  OTHER SUBLEASE TERMS:

          A.   INCORPORATION BY REFERENCE: Except as set forth below, the terms
and conditions of this Sublease shall include all of the terms of the Master
Lease and such terms are incorporated into this Sublease as if fully set forth
herein, except that: (i) each reference in such incorporated sections to "Lease"
shall be deemed a reference to "Sublease"; (ii) each reference to the "Demised
Premises" shall be deemed a reference to the "Subleased Premises"; (iii) each
reference to "Landlord" and "Tenant" shall be deemed a reference to "Sublessor"
and "Sublessee", respectively, except as otherwise expressly set forth herein;
(iv) with respect to work, services, repairs, restoration, insurance,
indemnities, representations, warranties or the performance of any other
obligation of Master Lessor under the Master Lease, the sole obligation of
Sublessor shall be to request the same in writing from Master Lessor as and when
requested to do so by Sublessee, and to use Sublessor's reasonable efforts
(without requiring Sublessor to spend more than a nominal sum) to obtain Master
Lessor's performance; (v) with respect to any obligation of Sublessee to be
performed under this Sublease, wherever the Master Lease grants to Sublessor a
specified number of days to perform its obligations under the Lease, except as
otherwise provided herein. Sublessee shall have three (3) fewer days to perform
the obligation, including, without limitation, curing any defaults; (vi) with
respect to any approval required to be obtained from the "Landlord" under the
Master Lease, such consent must be obtained from both Master Lessor and
Sublessor, and the approval of Sublessor shall not be unreasonably withheld or
delayed, but may be withheld if Master Lessor's consent is not obtained; (vii)
in any case where the "Landlord" reserves or is granted the right to


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manage, supervise, control, repair or enter the Premises or any areas beneath,
above or adjacent thereto, such reservation or grant of right of entry shall be
deemed to be for the benefit of both Master Lessor and Sublessor; except in the
case of certain employees of Senomyx who have been granted exit and entry
access through Additional Space III by use of a designated keycard, (viii) in
any case where "Tenant" is to indemnify, release or waive claims against
"Landlord", such indemnity, release or waiver shall be deemed to run from
Sublessee to both Master Lessor and Sublessor; and (ix) in any case where
"Tenant" is to execute and deliver certain documents or notices to "Landlord",
such obligation shall be deemed to run from Sublessee to Sublessor.

     Notwithstanding the foregoing: (a) the following provisions are not
incorporated herein: the introductory paragraph, the Recitals, Sections 1 - 6,
8.6, 9, 10.1 10.7 (except the first sentence), 11, 17.11 (the first sentence
only), 24.11, 25.3, 31, 36.3, 37.3, 41.1 (the fifth through eighth sentences
only), 43.11 and 44-46, and Exhibits A-C, F and H-J; (b) references in the
following provisions to "Landlord" shall mean "Master Lessor": Sections 7.1,
14.1 (except the first two sentences), 15.3, 16.7 (the first sentence only),
16.8, 16.9, 17.6, 17.10, 18.1 (except the last reference), 18.2 (the first
sentence only), 21.1, 21.2, 22, 23, 32 and 36; (c) references in the following
provisions to "Landlord" shall mean "Master Lessor" or "Sublessor": Sections
10.2, 13, 17.8, 17.9, 18.2 (fifth sentence only) and 19; (d) references "in the
following provisions to "Landlord" shall mean "Master Lessor" and "Sublessor":
Sections 21.4, 21.6 and 35, (e) references to "Tenant" in Section 7.1 shall mean
"Sublessor"; and (f) references to "Tenant's Pro Rata Share" shall mean 5% for
Suite 250, 1.5% for Space I, 1.1% for Space II, 0.3% for Space III, 2% for Labs
38-40, 7.33% for Suite 220, 12.1% for Additional Space I, 1.4% for Additional
Space II, and 11.2% for Additional Space III (as may be adjusted by the Master
Lessor).

          B.   SUBORDINATE. This Sublease is and at all times shall be subject
and subordinate to the Master Lease and the rights of Master Lessor thereunder.
In the event of a conflict between the provisions of this Sublease and the
Master Lease, as between Sublessor and Sublessee, the provisions of this
Sublease shall control.

     18.  CONDITIONS PRECEDENT: This Sublease and Sublessor's and Sublessee's
obligations hereunder are conditioned upon the written consent of Master Lessor.
If Sublessor fails to obtain Master Lessor's consent within thirty (30) days
after execution of this Sublease by Sublessor, then Sublessor or Sublessee may
terminate this Sublease by giving the other party written notice thereof.

     19.  SUBLESSOR INDEMNITY: Sublessor shall indemnify, defend, protect, and
hold Sublessee harmless from and against all actions, claims, demands, costs,
liabilities, losses, reasonable attorneys' fees, damages, penalties and expenses
which may be brought or made against Sublessee or which Sublessee may pay or
incur to the extent caused by (i) a breach of this Sublease or the Master Lease
by Sublessor, (ii) the gross negligence or willful misconduct of Sublessor or
its agents, officers, directors, invitees or guests or (iii) obligations of
Sublessor which arise prior to the commencement date of this Sublease.


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     20.  EARLY TERMINATION/MODIFICATION OF MASTER LEASE: If the Master Lease
should terminate prior to the expiration of this Sublease for any reason.
Sublessor shall have no liability to Sublessee.

     21.  STATUS OF LEASE: Sublessor hereby represents and warrants to Sublessee
that (i) the Master Lease attached hereto as EXHIBIT A has been executed and
delivered by Master Lessor and Sublessor and constitutes the entire agreement of
the parties thereto relating to the lease of the Subleased Premises, (ii) no
default or breach by Sublessor exists under the Master Lease, (iii) no event has
occurred that, with the passage of time, the giving of notice, or both, would
constitute a default or breach by Sublessor, and (iv) subject to receipt of
Master Lessor's written consent hereto. Sublessor has the right and power to
execute and deliver this Sublease and to perform its obligations hereunder.

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

SUBLESSOR:                               SUBLESSEE:

SENOMYX, INC.,                           AKKADIX CORPORATION,
a Delaware corporation                   a California Corporation


By: /s/ Paul Grayson                    By: /s/ David Cohen
   -----------------------------           -----------------------------
Name: Paul A. Grayson                   Name: David Cohen
     ---------------------------             ---------------------------
Its: President & CEO                    Its: Chief Financial Officer
    ----------------------------            ----------------------------

Address: 11099 North Torrey Pines Road   Address: 11099 North Torrey Pines Road
Suite 160                                Suite 200
La Jolla, California 92037               La Jolla, California 92037
Attn: Corporate Counsel                  Attn: Chief Financial Officer


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