SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                                (Amendment No. 1)

                          LEXICON GENETICS INCORPORATED
                                (Name of Issuer)

                     COMMON STOCK $0.001 PAR VALUE PER SHARE
                         (Title of Class of Securities)

                                   528872 10 4
                                 (CUSIP Number)

                                DECEMBER 31, 2001
             (Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

[ ]    Rule 13d-1(b)
[ ]    Rule 13d-1(c)
[X]    Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).

- -----------------------                                     --------------------
 CUSIP NO. 528872 10 4                13G                    PAGE 2 OF 5 PAGES
- --------------------------------------------------------------------------------
          NAMES OF REPORTING PERSONS
1         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

          Gordon A. Cain
- --------------------------------------------------------------------------------

          CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP     (A) [ ]
2
                                                               (B) [ ]
- --------------------------------------------------------------------------------
          SEC USE ONLY
3
- --------------------------------------------------------------------------------
          CITIZENSHIP OR PLACE OF ORGANIZATION
4
          United States of America
- --------------------------------------------------------------------------------
                              SOLE VOTING POWER
      NUMBER OF         5
        SHARES                    10,991,000
     BENEFICIALLY       --------------------------------------------------------
       OWNED BY               SHARED VOTING POWER
         EACH           6
      REPORTING                    2,000,000
        PERSON          --------------------------------------------------------
         WITH                 SOLE DISPOSITIVE POWER
                        7
                                  10,991,000
                        --------------------------------------------------------
                              SHARED DISPOSITIVE POWER
                        8
                                   2,000,000
- --------------------------------------------------------------------------------
          AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
9
                            12,991,000
- --------------------------------------------------------------------------------
          CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES
10        [ ]
- --------------------------------------------------------------------------------
          PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
11
                                     25.0%
- --------------------------------------------------------------------------------
          TYPE OF REPORTING PERSON*
12
                   IN
- --------------------------------------------------------------------------------

                                  Page 2 of 5

                                  SCHEDULE 13G

         Introductory Note: All information with respect to Lexicon Genetics
Incorporated is to the best knowledge and belief of the Reporting Person, as
defined herein.

ITEM 1.

         (a)      NAME OF ISSUER. The name of the issuer is Lexicon Genetics
                  Incorporated (the "Issuer").

         (b)      ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES. The address
                  of the Issuer's Principal Executive Offices is 4000 Research
                  Forest Drive, The Woodlands, Texas 77381.

ITEM 2.

         (a)      NAME OF PERSON FILING. The name of the person filing this
                  Schedule 13G is Gordon A. Cain (the "Reporting Person").

         (b)      ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE.
                  The address of the Reporting Person is 8 Greenway Plaza, Suite
                  702, Houston, Texas 77046.

         (c)      CITIZENSHIP. The reporting person is a citizen of the United
                  States.

         (d)      TITLE OF CLASS OF SECURITIES. The class of securities of the
                  Issuer owned beneficially by the Reporting Person is common
                  stock, $0.001 par value (the "Common Stock").

         (e)      CUSIP NUMBER. The CUSIP Number for the Common Stock is 528872
                  10 4.

ITEM 3. IF THIS STATEMENT IS FILED PURSUANT TO SECTIONS 240.13d-1(b) OR
240.13d-2(b) OR (c), CHECK WHETHER THE FILING PERSON IS:

    (a) [ ] Broker or dealer registered under section 15 of the Act
            (15 U.S.C. 78o).

    (b) [ ] Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

    (c) [ ] Insurance company as defined in section 3(a)(19) of the Act
            (15 U.S.C. 78c).

    (d) [ ] Investment company registered under section 8 of the Investment
            Company Act of 1950 (15 U.S.C. 80a-8).

    (e) [ ] An investment adviser in accordance with Section
            240.13d-(b)(1)(ii)(E);

    (f) [ ] An employee benefit plan of endowment fund in accordance with
            Section 240.13d(b)(1)(ii)(F);

    (g) [ ] A parent holding company or control person in accordance with
            Section 240.13d-1(b)(1)(ii)(G);

    (h) [ ] A savings associations as defined in Section 3(b) of the Federal
            Deposit Insurance Act (!2 U.S.C. 1813);

    (i) [ ] A church plan that is excluded from the definition of an investment
            company under section 3(c)(14) of the Investment Company Act of 1940
            (15 U.S.C. 80a-3);

    (j) [ ] Group, in accordance with Section 240.13d-(b)(1)(ii)(J).

                                  Page 3 of 5

ITEM 4.  OWNERSHIP.

         (a)      AMOUNT BENEFICIALLY OWNED. The amount of securities
                  beneficially owned by the Reporting Person is 12,991,000
                  shares of Common Stock.

         (B)      PERCENT OF CLASS. The percent of the class of Common Stock
                  beneficially owned by the Reporting Person is 25.0%.

         (C)      NUMBER OF SHARES AS TO WHICH THE PERSON HAS:

                  (i)      SOLE POWER TO VOTE OR TO DIRECT THE VOTE: 10,991,000

                  (ii)     SHARED POWER TO VOTE OR TO DIRECT THE VOTE:
                           2,000,000*

                  (iii)    SOLE POWER TO DISPOSE OR TO DIRECT THE DISPOSITION
                           OF: 10,991,000

                  (iv)     SHARED POWER TO DISPOSE OR TO DIRECT THE DISPOSITION
                           OF: 2,000,000*

* These shares are owned by the Gordon and Mary Cain Foundation, of which Gordon
A. Cain is the chairman and a trustee.

ITEM 5.  OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.

         If this statement is being filed to report the fact that as of the date
hereof the reporting person has ceased to be the beneficial owner of more than
five percent of the class of securities, check the following: [ ]

ITEM 6.  OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.

Not Applicable.

ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE
SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY OR CONTROL PERSON.

         Not Applicable.

ITEM 8.  IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP.

         Not Applicable.

ITEM 9.  NOTICE OF DISSOLUTION OF GROUP.

         Not applicable.

ITEM 10.  CERTIFICATION.

         By signing below I certify that, to the best of my knowledge and
belief, the securities referred to above were not acquired and are not held for
the purpose of or with the effect of changing or influencing the control of the
issuer of the securities and were not acquired and are not held in connection
with or as a participant in any transaction having that purpose or effect.

                                  Page 4 of 5

                                    SIGNATURE

         After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Date:    February 11, 2002

                                     /s/ JOHN M. SULLIVAN
                                     ---------------------
                                     John M. Sullivan

                                     Signed pursuant to a
                                     Durable Power of Attorney
                                     Dated February 8, 2002
                                     (attached hereto as
                                     Exhibit 1)

                                  Page 5 of 5

                               INDEX TO EXHIBITS

EXHIBIT
- -------

 99.1           Statutory Durable Power of Attorney

                                                                       EXHIBIT 1

                      STATUTORY DURABLE POWER OF ATTORNEY
                            EFFECTIVE UPON EXECUTION

NOTICE: THE POWERS GRANTED BY THIS DOCUMENT ARE BROAD AND SWEEPING. THEY ARE
EXPLAINED IN THE DURABLE POWER OF ATTORNEY ACT, CHAPTER XII, TEXAS PROBATE CODE.
THIS DOCUMENT DOES NOT AUTHORIZE ANYONE TO MAKE MEDICAL AND OTHER HEALTH CARE
DECISIONS FOR THE PRINCIPAL. THIS POWER OF ATTORNEY MAY BE REVOKED AT ANY TIME.

         I, GORDON A. CAIN, live at 2121 Kirby Drive, #9E, Houston, Texas 77019.
I appoint JOHN M. SULLIVAN as my agent (attorney-in-fact) to act for me in any
lawful way with respect to all of the following powers, except for any I have
crossed out below.

                  Real Property Transactions;
                  Tangible Personal Property Transactions;
                  Stock and Bond Transactions;
                  Commodity and Option Transactions;
                  Banking and Other Financial Institution Transactions;
                  Business Operating Transactions;
                  Insurance and Annuity Transactions;
                  Estate, Trust, and Other Beneficiary Transactions;
                  Claims and Litigation;
                  Personal and Family Maintenance;
                  Benefits from Social Security, Medicare, Medicaid, or Other
                         Governmental Programs or Civil or Military Services;
                  Retirement Plan Transactions; and
                  Tax Matters.

IF NO POWER LISTED ABOVE IS CROSSED OUT, THIS DOCUMENT SHALL BE CONSTRUED AND
INTERPRETED AS A GENERAL POWER OF ATTORNEY AND MY AGENT (ATTORNEY-IN-FACT) SHALL
HAVE THE POWER AND AUTHORITY TO PERFORM OR UNDERTAKE ANY ACTION I COULD PERFORM
OR UNDERTAKE IF I WERE PERSONALLY PRESENT.

I.       ADDITIONAL SPECIFIC POWERS.

         A.       Insurance and Retirement Plans. My agent shall have the power
to designate or change the beneficiary of an insurance contract, annuity
contract or retirement plan, except that an attorney in fact or agent may be a
named beneficiary of the contract or plan or an extension, renewal, or
substitute for the contract or plan only to the extent the attorney in fact or
agent was a beneficiary named under a contract or plan before this Power of
Attorney became effective.

         B.       Ratification and General Grant of Power. I hereby ratify and
confirm all that my agent may do pursuant to this Power of Attorney. I recognize
that powers of attorney are sometimes strictly construed and it is not my
intention by listing the above-enumerated powers to limit the

power and authority of my agent. In addition to the above-enumerated powers,
except as specifically provided above, my agent is authorized and empowered, for
me and in my name, to do any and every act and exercise any and every power that
I might or could do or exercise through any other person and that my agent shall
deem proper or advisable. I intend to vest in my agent a full and universal
power of attorney.

II.      OTHER POWERS OF ATTORNEY. The validity of this Power of Attorney shall
not be affected in any manner by reason of the execution, at any time, of powers
of attorney by me in favor of persons other than those named herein.

III.     RELIANCE ON AFFIDAVIT OF LACK OF KNOWLEDGE OF TERMINATION OF POWER. My
agent may execute an affidavit stating that he did not have actual knowledge of
revocation of this Power of Attorney by reason of my death, the qualification of
a guardian of my estate, divorce, marriage annulment, or pursuant to the
following Paragraph at the time he exercised this Power of Attorney, and such
affidavit shall be conclusive proof as between my agent and another person
(other than me or my personal representative) of my agent's lack of actual
knowledge of the revocation of this Power of Attorney.

IV.      REVOCATION.  I agree and represent to those dealing with my agent that
this Power of Attorney may be voluntarily revoked only by written revocation
recorded in the Official Public Records of Real Property (Deed Records) of
Harris County, Texas. Revocation of this Power of Attorney is not effective as
to a third party until the third party receives actual notice of the revocation.

V.       AGREEMENT AS TO THIRD PARTY RELIANCE.  I agree that any third party who
receives a copy of this Power of Attorney may act under it.

VI.      INDEMNITIES.  I agree to indemnify the third party for any claims that
arise against the third party because of reliance on this Power of Attorney. I
authorize my agent to indemnify and hold harmless any third party who accepts
and acts under this Power of Attorney.

VII.     EFFECTIVE DATE.  This Power of Attorney shall be effective immediately.
It is not affected by my subsequent disability or incapacity and shall remain
effective in the event of my disability or incapacity.

         Signed this 8th day of February, 2002.

                                                  /s/ GORDON A. CAIN
                                                  ------------------------------
                                                  Gordon A. Cain

                                      -2-

STATE OF TEXAS

COUNTY OF HARRIS

         BEFORE ME, the undersigned authority, on this day personally appeared
Gordon A. Cain, known to me to be the person whose name is subscribed to the
foregoing instrument, and acknowledged to me that he executed the same for the
purposes and consideration therein expressed.

         GIVEN UNDER MY HAND AND SEAL OF OFFICE this, the 8th day of February,
2002.

                                             /s/ PAMELA LYNN HENTHORNE
                  [SEAL]                     ----------------------------------
                                             Notary Public in and for the
                                             State of Texas

THE ATTORNEY-IN-FACT OR AGENT, BY ACCEPTING OR ACTING UNDER THIS POWER OF
ATTORNEY, ASSUMES THE FIDUCIARY AND OTHER LEGAL RESPONSIBILITIES OF AN AGENT.

                                      -3-