Document:

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                                                                     EXHIBIT 4.1

                            INVESTOR RIGHTS AGREEMENT

                                 by and between

                            OSI PHARMACEUTICALS, INC.
                             a Delaware corporation

                                       and

                             GILEAD SCIENCES, INC.,
                             a Delaware corporation

                          Dated as of December 21, 2001
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                            INVESTOR RIGHTS AGREEMENT

         THIS INVESTOR RIGHTS AGREEMENT is being entered into as of December 21,
2001, by and between OSI PHARMACEUTICALS, INC., a Delaware corporation (the
"Company"), and GILEAD SCIENCES, INC., a Delaware corporation (the "Investor").
Capitalized terms not defined herein shall have the meaning ascribed to them in
that certain Asset Purchase Agreement, dated as of November 26, 2001, by and
between the Company, as the purchaser, and the Investor, as the seller (the
"Purchase Agreement").

                                    RECITALS

         WHEREAS, pursuant to the Purchase Agreement, the Company is purchasing
from the Investor, and the Investor is selling to the Company, certain assets
(the "Specified Assets");

         WHEREAS, as partial consideration for the Specified Assets, the Company
is issuing to the Investor 924,984 shares (the "Initial Shares") of the
Company's common stock, $.01 par value per share (the "Common Stock");

         WHEREAS, as additional consideration for the Specified Assets, upon the
satisfaction of certain conditions set forth in the Purchase Agreement, the
Company may issue additional shares of Common Stock to the Investor (as set
forth in Section 1.3(d) of the Purchase Agreement, the "Subsequent Shares"); and

         WHEREAS, the Company has agreed to grant to the Investor certain rights
to cause the Company to register, under the Securities Act of 1933, as amended,
the offer and sale of the Initial Shares and Subsequent Shares.

         NOW, THEREFORE, in consideration of the premises and the mutual
promises made herein and for other good and valuable consideration, the receipt
and sufficiency of which is hereby acknowledged, the parties hereto, intending
to be legally bound, agree as follows:

         1. Definitions. In addition to those terms defined above and elsewhere
in this Agreement, for the purposes of this Agreement, the following terms shall
have the meanings set forth here:

                  1.1. "Affiliate" shall mean, with respect to any Person, any
other Person which directly or indirectly controls, is controlled by, or is
under common control with, such Person.

                  1.2. "Closing Date" shall have the meaning set forth in the
Purchase Agreement.

                  1.3. "Common Stock" shall have the meaning set forth in the
Recitals.

                  1.4. "Company" shall have the meaning set forth in the
Heading.

                  1.5. "Exchange Act" shall mean the Securities Exchange Act of
1934, as amended, and the rules and regulations promulgated thereunder.

                  1.6. "Initial Shares" shall have the meaning set forth in the
Recitals.

                  1.7. "Investor" shall have the meaning set forth in the
Heading.

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                  1.8. "NASD" shall mean the National Association of Securities
Dealers, Inc.

                  1.9. "Nasdaq National Market" shall mean The Nasdaq Stock
Market, Inc. National Market.

                  1.10. "Person" shall mean an individual, corporation,
partnership, trust, business trust, association, joint stock company, joint
venture, pool, syndicate, sole proprietorship, unincorporated organization,
governmental authority or any other form of entity not specifically listed
herein.

                  1.11. "Purchase Agreement" shall have the meaning set forth in
the Heading.

                  1.12. "Registration Statement" shall mean a registration
statement filed pursuant to Section 3.1(a) or 3.1(b).

                  1.13. "SEC" shall mean the United States Securities and
Exchange Commission.

                  1.14. "Securities Act" shall mean the Securities Act of 1933,
as amended, and the rules and regulations promulgated thereunder.

                  1.15. "Shares" shall mean the Initial Shares and the
Subsequent Shares.

                  1.16. "Specified Assets" shall have the meaning set forth in
the Recitals.

                  1.17. "Subsequent Shares" shall have the meaning set forth in
the Recitals.

                  1.18. "Suspension" shall have the meaning set forth in Section
3.2(c).

                  1.19. "Suspension Notice" shall have the meaning set forth in
Section 3.2(c).

         2. Representations, Warranties and Covenants of the Investor.

                  2.1. Representations and Warranties. The Investor hereby
represents and warrants to the Company as follows:

                           (a) Accredited Investor, Investment Decision.

                                    (i) The Investor is an "accredited investor"
as defined in Regulation D under the Securities Act and is knowledgeable,
sophisticated and experienced in making investments of the type contemplated by
the Purchase Agreement and this Agreement.

                                    (ii) The Investor has requested, received,
reviewed and considered all information it has deemed relevant in making an
informed decision to acquire the Shares.

                                    (iii) The Investor is acquiring the Shares
for its own account for investment only and with no present intention of
distributing any of the Shares and has no arrangement or understanding with any
other Persons regarding the distribution of the Shares.

                                    (iv) The Investor understands that its
acquisition of the Shares has not been registered under the Securities Act or
registered or qualified under any state securities law in

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reliance on specific exemptions therefrom, which exemptions may depend upon,
among other things, the bona fide nature of the Investor's investment intent as
expressed in this Agreement.

                           (b) NASD. The Investor has no direct or indirect
affiliation or association with any member of the NASD as of the date hereof.

                           (c) Restricted Securities, Legends. The Investor
understands that the Initial Shares are, and the Subsequent Shares will be,
characterized as "restricted securities" under the Securities Act inasmuch as
they are being acquired from the Company in a transaction not involving a public
offering and that under such law and applicable regulations such securities may
be resold without registration under the Securities Act only in certain limited
circumstances. The Investor understands that certificates evidencing the Shares
may bear one or all of the following legends:

                  "The shares represented by this certificate have not been
                  registered under the Securities Act of 1933, as amended (the
                  "Act"), and may not be transferred without (i) an opinion of
                  counsel satisfactory to the corporation that such transfer may
                  lawfully be made without registration under such Act or
                  qualification under applicable state securities laws; or (ii)
                  such registration or qualification, except for a transfer in
                  compliance with Rule 144 under the Act."

                  If required by the authorities of any state in connection with
                  the issuance of sale of the Shares, the legend required by
                  such state authority.

Any purchaser of the Shares pursuant to an effective registration statement
under the Securities Act will be entitled to receive a certificate bearing no
restrictive legend.

                  2.2. Covenants. The Investor hereby covenants with the Company
as follows:

                           (a) The Investor will not, directly or indirectly,
offer, sell, pledge, transfer or otherwise dispose of (or solicit any offers to
buy, purchase or otherwise acquire or take a pledge of) any of the Shares except
in compliance with the Securities Act and applicable state securities laws. In
furtherance thereof, the Investor will not make any disposition of the Shares
except (i) pursuant to a registration statement under the Securities Act
covering such proposed disposition, (ii) upon prior notice to the Company and,
if reasonably requested by the Company, delivery to the Company of an opinion of
counsel, reasonably satisfactory to the Company, that such disposition will not
require registration under the Securities Act, or (iii) in compliance with Rule
144 under the Securities Act. In addition, and not in limitation of the
foregoing, the Investor agrees that, during the 90-day period following the
Closing, it will not sell or otherwise dispose of more than 50% of the Shares.

                           (b) The Investor acknowledges and agrees that no
action has been or will be taken in any jurisdiction outside the United States
by the Company that would permit an offering of the Shares, or possession or
distribution of offering materials in connection with the issuance of the
Shares, in any jurisdiction outside the United States where legal action by the
Company for that purpose is required. The Investor outside the United States
will comply with all applicable laws and regulations in each foreign
jurisdiction in which it purchases, offers, sells or delivers Shares or has in
its possession or distributes any offering material, in all cases at its own
expense.

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         3. Registration of the Shares; Compliance With the Securities Act.

                  3.1. Registration Procedures and Expenses. The Company shall:

                           (a) subject to prompt receipt of necessary
information from the Investor after prompt request from the Company to the
Investor to provide such information, use reasonable best efforts to prepare and
file with the SEC, by the later of (i) five business days after the Closing Date
of the Purchase Agreement; or (ii) January 2, 2002, a shelf registration
statement to enable the resale of the Shares by the Investor from time to time
on a delayed or continuous basis pursuant to Rule 415 of the Securities Act
through the automated quotation system of the Nasdaq National Market or such
other market as may be the principal market on which the Company's Common Stock
is sold, or any other manner reasonably requested by the Investor, including
privately-negotiated transactions;

                           (b) in the event the SEC does not permit the Company
to register the Subsequent Shares pursuant to the registration statement filed
in accordance with Section 3.1(a), subject to prompt receipt of necessary
information from the Investor after prompt request from the Company to the
Investor to provide such information, use reasonable best efforts to prepare and
file with the SEC, within five business days following satisfaction of the
conditions set forth in Section 1.3(d) of the Purchase Agreement for the
issuance by the Company of the Subsequent Shares, a shelf registration statement
to enable the resale of the Subsequent Shares by the Investor from time to time
on a delayed or continuous basis pursuant to Rule 415 of the Securities Act
through the automated quotation system of the Nasdaq National Market or such
other market as may be the principal market on which the Company's Common Stock
is sold, or any other manner reasonably requested by the Investor, including
privately-negotiated transactions;

                           (c) use reasonable best efforts, subject to receipt
of necessary information from the Investor after prompt request from the Company
to the Investor to provide such information, to cause the Registration Statement
to become effective as soon as practicable after the Registration Statement is
filed by the Company;

                           (d) use reasonable best efforts to prepare and file
with the SEC such amendments and supplements to the Registration Statement and
the prospectus used in connection therewith as may be necessary to keep the
Registration Statement current and effective until the later of (i) two years
after the Closing Date or (ii) all of the Shares may be sold pursuant to Rule
144 of the Securities Act without regard to any volume limitations;

                           (e) furnish to the Investor such number of copies of
the Registration Statement, prospectuses and preliminary prospectuses in
conformity with the requirements of the Securities Act and such other documents
as the Investor may reasonably request, in order to facilitate the public sale
or other disposition of all or any of the Shares by the Investor; provided,
however, that the obligation of the Company to deliver copies of prospectuses or
preliminary prospectuses to the Investor shall be subject to the receipt by the
Company of reasonable assurances from the Investor that the Investor will comply
with the applicable provisions of the Securities Act and of such other
securities or blue sky laws as may be applicable in connection with any use of
such prospectuses or preliminary prospectuses;

                           (f) take all reasonable actions necessary to ensure
that the Initial Shares and any Subsequent Shares are listed and available for
quotation on The Nasdaq National Market;

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                           (g) file documents required of the Company for normal
blue sky clearance in states specified in writing by the Investor; provided,
however, that the Company shall not be required to qualify to do business or
consent to service of process in any jurisdiction in which it is not now so
qualified or has not so consented;

                           (h) use reasonable efforts to assist the Investor
with any proposed sale of the Shares by the Investor;

                           (i) bear all expenses (exclusive of underwriting
discounts and commissions) in connection with the procedures in paragraph (a)
through (e) of this Section 3.1 and the registration of the Shares pursuant to
the Registration Statement, including reasonable fees and expenses of counsel to
the Investor not to exceed $7,500; and

                           (j) advise the Investor promptly after it shall
receive notice or obtain knowledge of the issuance of any stop order by the SEC
delaying or suspending the effectiveness of the Registration Statement or of the
initiation or threat of any proceeding for that purpose; and it will promptly
use commercially reasonable efforts to prevent the issuance of any stop order or
to obtain its withdrawal at the earliest possible moment if such stop order
should be issued.

         The Company understands that the Investor disclaims being an
underwriter, but the Investor's being deemed an underwriter by the SEC shall not
relieve the Company of any obligations it has hereunder.

                  3.2. Transfer of Shares After Registration; Suspension.

                           (a) The Investor agrees that it will not effect any
disposition of the Shares or its right to purchase the Shares that would
constitute a sale within the meaning of the Securities Act except as
contemplated in the Registration Statement referred to in Section 3.1 and as
described below or as otherwise permitted by law, and that it will promptly
notify the Company of any changes in the information set forth in the
Registration Statement regarding the Investor or its plan of distribution.

                           (b) Except in the event that paragraph (c) below
applies, the Company shall (i) if deemed necessary by the Company, prepare and
file from time to time with the SEC a post-effective amendment to the
Registration Statement or a supplement to the related prospectus or a supplement
or amendment to any document incorporated therein by reference or file any other
required document so that such Registration Statement will not contain an untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary to make the statements therein not misleading, and
so that, as thereafter delivered to purchasers of the Shares being sold
thereunder, such prospectus will not contain an untrue statement of a material
fact or omit to state a material fact required to be stated therein or necessary
to make the statements therein, in light of the circumstances under which they
were made, not misleading; (ii) provide the Investor copies of any documents
filed pursuant to this Section 3.2(b)(i); and (iii) inform the Investor that the
Company has complied with its obligations in this Section 3.2(b)(i) (or that, if
the Company has filed a post-effective amendment to the Registration Statement
which has not yet been declared effective, the Company will notify the Investor
to that effect, will use commercially reasonable efforts to secure the
effectiveness of such post-effective amendment as promptly as possible and will
promptly notify the Investor pursuant to this Section 3.2(b)(i) when the
amendment has become effective).

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                           (c) Subject to paragraph (d) below, in the event (i)
of any request by the SEC or any other federal or state governmental authority
during the period of effectiveness of the Registration Statement for amendments
or supplements to a Registration Statement or related prospectus or for
additional information; (ii) of the issuance by the SEC or any other federal or
state governmental authority of any stop order suspending the effectiveness of a
Registration Statement or the initiation of any proceedings for that purpose;
(iii) of the receipt by the Company of any notification with respect to the
suspension of the qualification or exemption from qualification of any of the
Shares for sale in any jurisdiction or the initiation or threatening of any
proceeding for such purpose; or (iv) of any event or circumstance which, upon
the advice of its counsel, necessitates the making of any changes in the
Registration Statement or prospectus, or any document incorporated or deemed to
be incorporated therein by reference, so that, in the case of the Registration
Statement, it will not contain any untrue statement of a material fact or any
omission to state a material fact required to be stated therein or necessary to
make the statements therein not misleading, and that in the case of the
prospectus, it will not contain any untrue statement of a material fact or any
omission to state a material fact required to be stated therein or necessary to
make the statements therein, in the light of the circumstances under which they
were made, not misleading; then the Company shall promptly deliver a certificate
in writing to the Investor (the "Suspension Notice") to the effect of the
foregoing and, upon receipt of such Suspension Notice, the Investor will refrain
from selling any Shares pursuant to the Registration Statement (a "Suspension")
until the Investor's receipt of copies of a supplemented or amended prospectus
prepared and filed by the Company, or until it is advised in writing by the
Company that the current prospectus may be used, and has received copies of any
additional or supplemental filings that are incorporated or deemed incorporated
by reference in any such prospectus. In the event of any Suspension, the Company
will use its reasonable best efforts to cause the use of the prospectus so
suspended to be resumed as soon as reasonably practicable. In addition to and
without limiting any other remedies (including, without limitation, at law or at
equity) available to the Investor, the Investor shall be entitled to specific
performance in the event that the Company fails to comply with the provisions of
this Section 3.2(c).

                           (d) Notwithstanding the foregoing paragraphs of this
Section 3.2, the Investor shall not be prohibited from selling the Shares under
the Registration Statement as a result of Suspensions on more than one occasion
of not more than thirty days in any twelve month period, unless, in the good
faith judgment of the Company's Board of Directors, upon advice of counsel, the
sale of the Shares under the Registration Statement would be reasonably likely
to cause a violation of the Securities Act or the Exchange Act and result in
liability to the Company.

                           (e) Provided that a Suspension is not then in effect,
the Investor may sell the Shares under the Registration Statement; provided,
however, that it arranges for delivery of a current prospectus to the transferee
of such Shares. Upon receipt of a request therefor, the Company has agreed to
provide an adequate number of current prospectuses to the Investor and to supply
copies to any other parties requiring such prospectuses.

                           (f) In the event of a sale of the Shares by the
Investor pursuant to the Registration Statement, the Investor must also deliver
to the Company's transfer agent, with a copy to the Company, a Certificate of
Subsequent Sale substantially in the form attached hereto as Exhibit A so that
the Shares may be properly transferred. Assuming timely delivery to the
Company's transfer agent of one or more stock certificates representing the
Shares in proper form for transfer and assuming compliance by the Investor with
the terms of this Agreement, the Company's transfer agent will issue and make
appropriate delivery of one or more stock certificates in the name of the buyer
so as to permit timely compliance by the Investor with applicable settlement
requirements.

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                  3.3. Assignment of Registration Rights. The rights to cause
the Company to register the Shares pursuant to this Agreement may be assigned
(but only with all related obligations) by the Investor to an Affiliate of the
Investor; provided: (i) the Company is, within a reasonable time after such
transfer, furnished with written notice of the name and address of such
transferee or assignee and the securities with respect to which such
registration rights are being assigned; (ii) such transferee or assignee agrees
in writing to be bound by and subject to the terms and conditions of this
Agreement; and (iii) such assignment shall be effective only if immediately
following such transfer the further disposition of such securities by the
transferee or assignee is restricted under the Securities Act.

                  3.4. Indemnification.

                           (a) Definitions. For the purpose of this Section 3.4:

                                    (i) the term "Selling Stockholder" shall
include the Investor and each person, if any, who controls the Investor within
the meaning of Section 15 of the Securities Act, including any officer,
director, trustee or Affiliate of such Investor;

                                    (ii) the term "Registration Statement" shall
include any final prospectus, exhibit, supplement or amendment included in or
relating to the Registration Statement referred to in Section 3.1; and

                                    (iii) the term "untrue statement" shall
include any untrue statement or alleged untrue statement, or any omission or
alleged omission to state in the Registration Statement a material fact required
to be stated therein or necessary to make the statements therein, in the light
of the circumstances under which they were made, not misleading.

                           (b) Indemnification by the Company Relating to the
Company's Representations and Warranties in the Purchase Agreement. The Company
represents and warrants to the Investor that all of the representations and
warranties of the Company set forth in the Purchase Agreement are accurate in
all respects as of the date hereof as if made on and as of the date hereof. The
Company agrees to indemnify and hold harmless the Investor and its agents,
directors, officers, employees, affiliates, successors and assigns (together
with Investor, the "Investor Indemnitees") from and against any losses, claims,
damages, liabilities or expenses which any of the Investor Indemnitees may
suffer or incur, or to which any of the Investor Indemnitees may become subject
(whether or not relating to any third-party claim), insofar as such losses,
claims, damages, liabilities or expenses (or actions or proceedings in respect
thereof) arise out of, are based upon or result directly or indirectly from, any
inaccuracy in or other breach of the representation and warranty set forth in
the first sentence of this Section 3.4(b).

                           (c) Indemnification by the Company. The Company
agrees to indemnify and hold harmless the Selling Stockholder from and against
any losses, claims, damages or liabilities to which such Selling Stockholder may
become subject (under the Securities Act or otherwise) insofar as such losses,
claims, damages or liabilities (or actions or proceedings in respect thereof)
arise out of, or are based upon, (i) any untrue statement of a material fact
contained in the Registration Statement, or (ii) any failure by the Company to
fulfill any undertaking included in the Registration Statement, and the Company
will reimburse such Selling Stockholder for any reasonable legal or other
expenses reasonably incurred in investigating, defending or preparing to defend
any such action, proceeding or claim; provided, however, that the Company shall
not be liable in any such case to the extent that such loss, claim, damage or
liability arises out of, or is based upon, an untrue statement made in such
Registration Statement in reliance upon and in conformity with written
information furnished to the

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Company by or on behalf of the Selling Stockholder specifically for use in
preparation of the Registration Statement or the failure of the Selling
Stockholder to comply with its covenants and agreements contained in this
Agreement respecting the sale of the Shares or any statement or omission in any
prospectus that is corrected in any subsequent prospectus that was delivered to
the Investor prior to the pertinent sale or sales by the Investor; provided
however, that the Selling Stockholder shall be entitled to be indemnified in any
such case for any statement or alleged statement in or omission or alleged
omission from such Registration Statement, preliminary prospectus, final
prospectus or summary prospectus contained therein, or any amendment or
supplement thereto, in which such statement or omission has been corrected, in
writing, by the Investor and delivered to the Company at least ten days before
the sale or sales from which such loss occurred. The Company shall reimburse the
Selling Stockholder for the amounts provided for herein on demand as such
expenses are incurred.

                           (d) Indemnification by the Investor. The Investor
agrees to indemnify and hold harmless the Company (and each person, if any, who
controls the Company within the meaning of Section 15 of the Securities Act,
each officer of the Company who signs the Registration Statement and each
director of the Company) from and against any losses, claims, damages or
liabilities to which the Company (or any such officer, director or controlling
person) may become subject (under the Securities Act or otherwise), insofar as
such losses, claims, damages or liabilities (or actions or proceedings in
respect thereof) arise out of, or are based upon, (i) any failure to comply with
the covenants and agreements contained in this Agreement respecting the sale of
the Shares, or (ii) any untrue statement of a material fact contained in the
Registration Statement if such untrue statement was made in reliance upon and in
conformity with written information furnished by or on behalf of the Investor
specifically for use in preparation of the Registration Statement, and the
Investor will reimburse the Company (or such officer, director or controlling
person), as the case may be, for any reasonable legal or other expenses
reasonably incurred in investigating, defending or preparing to defend any such
action, proceeding or claim; provided, however, that the Investor's obligation
to indemnify the Company shall be limited to the net amount received by the
Investor from the sale of the Shares; and further provided however, that the
Selling Stockholder shall have no obligation to indemnify the Company in any
such case for any statement or alleged statement in or omission or alleged
omission from such Registration Statement, preliminary prospectus, final
prospectus or summary prospectus contained therein, or any amendment or
supplement thereto, in which such statement or omission has been corrected, in
writing, by the Investor and delivered to the Company at least ten days before
the sale or sales from which such loss occurred.

                           (e) Notice of Claims, Etc. Promptly after receipt by
any indemnified person of a notice of a claim or the beginning of any action in
respect of which indemnity is to be sought against an indemnifying person
pursuant to this Section 3.4, such indemnified person shall notify the
indemnifying person in writing of such claim or of the commencement of such
action, but the omission to so notify the indemnifying party will not relieve it
from any liability which it may have to any indemnified party under this Section
3.4 (except to the extent that such omission materially and adversely affects
the indemnifying party's ability to defend such action) or from any liability
otherwise than under this Section 3.4. Subject to the provisions hereinafter
stated, in case any such action shall be brought against an indemnified person,
the indemnifying person shall be entitled to participate therein, and, to the
extent that it shall elect by written notice delivered to the indemnified party
promptly after receiving the aforesaid notice from such indemnified party, shall
be entitled to assume the defense thereof, with counsel reasonably satisfactory
to such indemnified person. After notice from the indemnifying person to such
indemnified person of its election to assume the defense thereof, such
indemnifying person shall not be liable to such indemnified person for any legal
expenses subsequently incurred by such indemnified person in connection with the
defense thereof; provided, however, that if

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there exists or shall exist a conflict of interest that would make it
inappropriate, in the opinion of counsel to the indemnified person, for the same
counsel to represent both the indemnified person and such indemnifying person or
any Affiliate or associate thereof, the indemnified person shall be entitled to
retain its own counsel at the expense of such indemnifying person; provided,
however, that no indemnifying person shall be responsible for the fees and
expenses of more than one separate counsel (together with appropriate local
counsel) for all indemnified parties. In no event shall any indemnifying person
be liable in respect of any amounts paid in settlement of any action unless the
indemnifying person shall have approved the terms of such settlement; provided,
however, that such consent shall not be unreasonably withheld. No indemnifying
person shall, without the prior written consent of the indemnified person,
effect any settlement of any pending or threatened proceeding in respect of
which any indemnified person is or could have been a party and indemnification
could have been sought hereunder by such indemnified person, unless such
settlement includes an unconditional release of such indemnified person from all
liability on claims that are the subject matter of such proceeding.

                           (f) Contribution. If the indemnification provided for
in this Section 3.4 is unavailable to or insufficient to hold harmless an
indemnified party under paragraph (c) or (d) above in respect of any losses,
claims, damages or liabilities (or actions or proceedings in respect thereof)
referred to therein, then each indemnifying party shall contribute to the amount
paid or payable by such indemnified party as a result of such losses, claims,
damages or liabilities (or actions in respect thereof) in such proportion as is
appropriate to reflect the relative fault of the Company on the one hand and the
Investor, as well as any other selling stockholders under such registration
statement on the other in connection with the statements or omissions or other
matters which resulted in such losses, claims, damages or liabilities (or
actions in respect thereof), as well as any other relevant equitable
considerations. The relative fault shall be determined by reference to, among
other things, in the case of an untrue statement, whether the untrue statement
relates to information supplied by the Company on the one hand or an Investor or
other selling stockholder on the other and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
untrue statement. The Company and the Investor agree that it would not be just
and equitable if contribution pursuant to this paragraph (f) were determined by
pro rata allocation (even if the Investor and other selling stockholders were
treated as one entity for such purpose) or by any other method of allocation
which does not take into account the equitable considerations referred to above
in this paragraph (f). The amount paid or payable by an indemnified party as a
result of the losses, claims, damages or liabilities (or actions in respect
thereof) referred to above in this paragraph (f) shall be deemed to include any
legal or other expenses reasonably incurred by such indemnified party in
connection with investigating or defending any such action or claim.
Notwithstanding the provisions of this paragraph (f), the Investor shall not be
required to contribute any amount in excess of the amount by which the net
amount received by the Investor from the sale of the Shares to which such loss
relates exceeds the amount of any damages which such Investor has otherwise been
required to pay by reason of such untrue statement. No person guilty of
fraudulent misrepresentation (within the meaning of Section 11(f) of the
Securities Act) shall be entitled to contribution from any person who was not
guilty of such fraudulent misrepresentation.

         4. Rule 144. The Company covenants that it will file the reports
required to be filed by it under the Securities Act and the Exchange Act and the
rules and regulations adopted by the SEC thereunder (or, if the Company is not
required to file such reports, it will, upon the request of the Investor, make
publicly available such information as necessary to permit sales pursuant to
Rule 144 under the Securities Act), and it will take such further action as the
Investor may reasonably request, all to the extent required from time to time to
enable the Investor to sell the Shares purchased hereunder without registration
under the Securities Act within the limitation of the exemptions provided by (a)
Rule 144 under the Securities Act, as such Rule may be amended from time to
time, or (b) any similar rule or

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regulation hereafter adopted by the SEC. Upon the request of the Investor, the
Company will deliver to it a written statement as to whether the Company has
complied with such information and requirements.

         5. Notices. All notices, requests, consents and other communications
hereunder shall be in writing, shall be mailed (a) if within domestic United
States by first-class registered or certified airmail, or nationally recognized
overnight express courier, postage prepaid, or by facsimile, or (b) if delivered
from outside the United States, by International Federal Express or facsimile,
and shall be deemed given (i) if delivered by first-class registered or
certified mail domestic, three business days after so mailed, (ii) if delivered
by nationally recognized overnight carrier, one business day after so mailed,
(iii) if delivered by International Federal Express, two business days after so
mailed, or (iv) if delivered by facsimile, upon electronic confirmation of
receipt and shall be delivered as addressed as follows:

                           (a) if to the Company, to:

                                  Robert L. Van Nostrand
                                  Vice President and Chief Financial Officer
                                  OSI Pharmaceuticals, Inc.
                                  58 South Service Road, Suite 110
                                  Melville, NY  11747
                                  Phone:  (631) 962-2000
                                  Telecopy:  (631) 752-3880

                                  with a copy to:

                                  Spencer W. Franck, Jr., Esquire
                                  Saul Ewing LLP
                                  1200 Liberty Ridge Drive
                                  Suite 200
                                  Wayne, PA 19087
                                  Phone:  (610) 251-5082
                                  Telecopy:  (610) 408-4405

                           (b) if to the Investor, at its address on the
                                  signature page hereto, or at such other
                                  address or addresses as may have been
                                  furnished to the Company in writing,

                                  with a copy to:

                                  Laura Berezin, Esquire
                                  Cooley Godward LLP
                                  Five Palo Alto Square
                                  3000 El Camino Real
                                  Palo Alto, CA  94306
                                  Phone:  (650) 843-5128
                                  Telecopy:  (650) 849-7400

                                       10
<PAGE>
         6. Governing Law. This Agreement will be construed in accordance with,
and governed in all respects by, the laws of the State of Colorado (without
giving effect to principles of conflicts of law).

         7. Venue and Jurisdiction. If any legal proceeding or other legal
action relating to this Agreement is brought or otherwise initiated, the venue
therefor will be in the State of Colorado, which will be deemed to be a
convenient forum. The Company and the Investor hereby expressly and irrevocably
consent and submit to the jurisdiction of the state and federal courts in the
State of Colorado.

         8. Parties in Interest. Nothing in this Agreement is intended to
provide any rights or remedies to any other Person other than the Company and
the Investor.

         9. Successors and Assigns. Except as provided in Section 3.3, this
Agreement may not be assigned by the Investor. Without the necessity of the
prior written consent of the Investor, but after notice duly given and in
compliance with this Agreement, the Company may assign its rights and delegate
its duties hereunder to any successor-in-interest corporation in the event of a
merger or consolidation of the Company with or into another corporation, or any
merger or consolidation of another corporation with or into the Company that
results directly or indirectly in an aggregate change in the ownership or
control of more than 50% of the voting rights of the equity securities of the
Company, or the sale of all or substantially all of the Company's assets. The
terms and conditions of this Agreement shall inure to the benefit of and be
binding upon the respective permitted successors and assigns of the parties.
Nothing in this Agreement, express or implied, is intended to confer upon any
party other than the parties hereto or their respective successors and assigns
any rights, remedies, obligations, or liabilities under or by reason of this
Agreement, except as expressly provided in this Agreement.

         10. Severability. In the event that any provision of this Agreement, or
the application of such provision to any Person or set of circumstances, shall
be determined to be invalid, unlawful, void or unenforceable to any extent, the
remainder of this Agreement, and the application of such provision to Persons or
circumstances other than those as to which it is determined to be invalid,
unlawful, void or unenforceable, will not be affected and will continue to be
valid and enforceable to the fullest extent permitted by law.

         11. Waiver. No failure on the part of either the Company or the
Investor to exercise any power, right, privilege or remedy under this Agreement,
and no delay on the part of either the Company or the Investor in exercising any
power, right, privilege or remedy under this Agreement, will operate as a waiver
thereof; and no single or partial exercise of any such power, right, privilege
or remedy will preclude any other or further exercise thereof or of any other
power, right, privilege or remedy.

         12. Amendments. This Agreement may not be amended, modified, altered or
supplemented except by means of a written instrument executed on behalf of both
parties.

         13. Counterparts. This Agreement may be executed in several
counterparts, each of which will constitute an original and all of which, when
taken together, will constitute one agreement.

         14. Interpretation of Agreement.

                  14.1. Each party acknowledges that it has participated in the
drafting of this Agreement, and any applicable rule of construction to the
effect that ambiguities are to be resolved against

                                       11
<PAGE>
the drafting party will not be applied in connection with the construction or
interpretation of this Agreement.

                  14.2. Whenever required by the context hereof, the singular
number will include the plural, and vice versa; the masculine gender will
include the feminine and neuter genders; and the neuter gender will include the
masculine and feminine genders.

                  14.3. As used in this Agreement, the words "include" and
"including," and variations thereof, will not be deemed to be terms of
limitation, and will be deemed to be followed by the words "without limitation."

                  14.4. The headings of the various sections of this Agreement
have been inserted for convenience of reference only and shall not be deemed to
be part of this Agreement.

                            [Signatures on next page]

                                       12
<PAGE>
         IN WITNESS WHEREOF, the parties have caused this Investor Rights
Agreement to be executed as of December 21, 2001.

                             THE COMPANY:

                             OSI PHARMACEUTICALS, INC.

                             By:         /s/ Geoffrey Cooper
                                      -----------------------------------------
                             Name:       Geoffrey Cooper
                             Title:      Vice President, Business Development
                             Address:    50 South Service Road, Suite 110
                                         Melville, NY  11747

                             THE INVESTOR:

                             GILEAD SCIENCES, INC.

                             By:         /s/ Mark L. Perry
                                      -----------------------------------------
                             Name:       Mark L. Perry
                             Title:      Executive Vice President, Operations
                             Address:

                                       13
<PAGE>
                                    EXHIBIT A

                         CERTIFICATE OF SUBSEQUENT SALE

Bank of New York
101 Barclay Street
New York, NY  10286

         RE:      Sale of Shares of Common Stock of OSI Pharmaceuticals, Inc.
                  (the "Company") pursuant to the Company's Prospectus
                  dated _____________, ____ (the "Prospectus")

Dear Sir/Madam:

         The undersigned hereby certifies, in connection with the sale of shares
of Common Stock of the Company included in the table of Selling Stockholders in
the Prospectus, that the undersigned has sold the shares pursuant to the
Prospectus and in a manner described under the caption "Plan of Distribution" in
the Prospectus and that such sale complies with all applicable securities laws,
applicable to the undersigned, including, without limitation, the Prospectus
delivery requirements of the Securities Act of 1933, as amended.

Selling Stockholder (the beneficial owner):

Record Holder (e.g., if held in name of nominee):
                                                  ------------------------------

Restricted Stock Certificate No.(s):
                                     -------------------------------------------

Number of Shares Sold:
                       ---------------------------------------

Date of Sale:
              ------------------------------------------------

         In the event that you receive a stock certificate(s) representing more
shares of Common Stock than have been sold by the undersigned, then you should
return to the undersigned a newly issued certificate for such excess shares in
the name of the Record Holder and BEARING A RESTRICTIVE LEGEND. Further, you
should place a stop transfer on your records with regard to such certificate.

                                         Very truly yours,

Dated:  _____________________            By:
                                             -----------------------------------

                                         Print Name:
                                                     ---------------------------

                                         Title:
                                                     ---------------------------

cc:      Robert L. Van Nostrand
         Vice President and Chief Financial Officer
         OSI Pharmaceuticals, Inc.
         58 South Service Road, Suite 110
         Melville, NY  11747

                                      A-1<PAGE>
                                                                    EXHIBIT 10.3

                                VOTING AGREEMENT

                  THIS VOTING AGREEMENT, dated as of October 22, 2001 (this
"Agreement"), among D.R. HORTON, INC., a Delaware corporation ("DHI") and the
record and beneficial stockholders of SCHULER HOMES, INC., a Delaware
corporation (the "Company"), whose names appear on Schedule I (collectively, the
"Stockholders").

                                   WITNESSETH:

                  WHEREAS, contemporaneously with the execution and delivery of
this Agreement, DHI and the Company are entering into an Agreement and Plan of
Merger, dated as of the date hereof (the "Merger Agreement"), which provides for
the merger (the "Merger") of the Company with and into DHI and the conversion of
all the outstanding shares of Class A Common Stock and Class B Common Stock,
each with a par value of $.001 per share, of the Company (collectively, the
"Shares") into cash and shares of common stock, par value $.01 per share, of
DHI;

                  WHEREAS, as of the date hereof, each Stockholder owns
(beneficially or of record) no less than the number of Shares set forth opposite
such Stockholder's name on Schedule I (all such Shares and any Shares which may
hereafter be acquired by such Stockholder prior to the termination of this
Agreement, whether upon the exercise of options or by means of purchase,
dividend, distribution or otherwise, (but not any other Shares owned by such
Stockholder on the date hereof but not set forth opposite such Stockholder's
name on Schedule I) being referred to herein as such Stockholder's "Subject
Shares");

                  WHEREAS, the parties to the Stockholders Agreement, dated as
of April 3, 2001, by and among the Company, the Stockholders and the other
parties thereto, have consented to this Agreement and waived the provisions of
such stockholders agreement to the extent inconsistent with the provisions of
this Agreement;

                  WHEREAS, this Agreement has been approved by the Board of
Directors of the Company and such approval is sufficient to render inapplicable
to the transactions contemplated hereby the provisions of Section 203 of the
Delaware Law;

                  WHEREAS, as a condition to their willingness to enter into the
Merger Agreement, DHI has required that the Stockholders enter into this Voting
Agreement; and

                  WHEREAS, in order to induce DHI to enter into the Merger
Agreement, the Stockholders are willing to enter into this Voting Agreement.

                  NOW, THEREFORE, in consideration of the foregoing and the
mutual covenants and agreements herein contained, and intending to be legally
bound hereby, DHI and each of the Stockholders, severally and not jointly,
hereby agree as follows:
<PAGE>

                                   ARTICLE I.

                         TRANSFER AND VOTING OF SHARES;
                     AND OTHER COVENANTS OF THE STOCKHOLDERS

                  SECTION 1.1. Voting of Shares. During the Term (as defined
below), at any meeting of the stockholders of the Company, however called, and
in any action by consent of the stockholders of the Company, each Stockholder
(a) shall appear at such meeting of the stockholders or otherwise cause the
Subject Shares such Stockholder owns beneficially or of record on the record
date of any such meeting or solicitation of consents to be counted as present
thereat for purposes of establishing a quorum and (b) shall vote its Subject
Shares (i) in favor of the Merger and the Merger Agreement (as amended from time
to time), (ii) against any proposal for a Third Party Acquisition and against
(A) any proposal for action or agreement that would result in a breach of any
covenant, representation or warranty or any other obligation or agreement of the
Company under the Merger Agreement or which is reasonably likely to result in
any of the conditions of the Company's obligations under the Merger Agreement
not being fulfilled, (B) any material change in the present capitalization of
the Company, (C) any other material change in the Company's corporate structure
or business or (D) any other action which could reasonably be expected to
impede, interfere with, delay, postpone or materially adversely affect the
transactions contemplated by the Merger Agreement or the likelihood of such
transactions being consummated and (iii) in favor of any other matter necessary
for consummation of the transactions contemplated by the Merger Agreement which
is considered at any such meeting of stockholders or the subject of any such
consent and in connection therewith to execute any documents which are necessary
or appropriate in order to effectuate the foregoing, including the ability for
DHI or its nominees to vote such Subject Shares directly.

                  SECTION 1.2. No Inconsistent Arrangements. During the Term,
except as contemplated by this Agreement and the Merger Agreement, no
Stockholder shall (i) transfer (which term shall include any sale, assignment,
gift, pledge, hypothecation or other disposition, whether directly or indirectly
by contribution, distribution, dissolution or otherwise), or consent to any
transfer of, any or all of such Stockholder's Subject Shares or any interest
therein, or create or, except as set forth on Schedule 1.2, permit to exist any
Encumbrance (as defined below) on such Subject Shares, (ii) enter into any
contract, option or other agreement or understanding with respect to any
transfer of any or all of such Subject Shares or any interest therein, (iii)
grant any proxy, power-of-attorney or other authorization in or with respect to
such Subject Shares, (iv) deposit such Subject Shares into a voting trust or
enter into a voting agreement or arrangement with respect to such Subject Shares
or (v) take any other action that would in any way restrict, limit or interfere
with the performance of its obligations hereunder or the transactions
contemplated hereby or by the Merger Agreement. Notwithstanding the foregoing,
James K. Schuler shall be permitted to transfer Subject Shares to his Affiliates
that are Stockholders and also parties to this Agreement. For purposes of this
Agreement, a transfer of membership interests in WPH-Schuler, LLC shall be
deemed not to be an indirect transfer of the Stockholder's Subject Shares so
long as such transferee acknowledges and consents to all of the provisions of
this Agreement.

                  SECTION 1.3. Proxy. In order to secure such Stockholder's
agreement to vote in accordance with Section 1.1, each Stockholder hereby
revokes any and all prior proxies or
<PAGE>

powers of attorney in respect of any of such Stockholder's Subject Shares and
constitutes and appoints DHI, or any nominee of DHI, with full power of
substitution and resubstitution, at any time during the Term, as its true and
lawful attorney and proxy (its "Proxy"), for and in its name, place and stead,
to demand that the Secretary of the Company call a special meeting of the
stockholders of the Company for the purpose of considering any matter referred
to in Section 1.1 (if permitted under the Company's certificate of incorporation
or bylaws) and to vote each of such Subject Shares as its Proxy, at every
annual, special, adjourned or postponed meeting of the stockholders of the
Company, including the right to sign its name (as stockholder) to any consent,
certificate or other document relating to the Company that Delaware Law may
permit or require as provided in Section 1.1.

                  THE FOREGOING PROXY AND POWER OF ATTORNEY ARE IRREVOCABLE AND
COUPLED WITH AN INTEREST THROUGHOUT THE TERM.

                  SECTION 1.4. Waiver of Appraisal Rights. Each Stockholder
hereby waives any rights of appraisal or rights to dissent from the Merger.

                  SECTION 1.5. Stop Transfer. No Stockholder shall request that
the Company register the transfer (book-entry or otherwise) of any certificate
or uncertificated interest representing any of such Stockholder's Subject
Shares, unless such transfer is made expressly subject to Section 3.4.

                  SECTION 1.6. No Solicitation. Upon execution of this
Agreement, each Stockholder shall, and it shall cause its Representatives to,
immediately cease any discussions or negotiations with any parties with respect
to any Third Party Acquisition. During the Term, no Stockholder shall, nor shall
any Stockholder authorize or permit any of its officers, directors, employees,
investment bankers, attorneys and other representatives or agents (collectively,
the "Representatives") to, directly or indirectly, encourage, solicit,
participate in or initiate discussions or negotiations with or provide any
information to any person or group (other than DHI or any designees of DHI)
concerning, or take any other action designed to facilitate any inquiries or the
making of any proposal concerning, any Third Party Acquisition. Each Stockholder
shall promptly (but no later than 24 hours after receipt) notify DHI in the
event it receives any proposal or inquiry concerning a Third Party Acquisition,
including the terms and conditions thereof and the identity of the party
submitting such proposal or inquiry (all in reasonable detail), and shall advise
DHI promptly of any developments concerning the same and the status thereof;
provided, however, that nothing herein shall prevent any Stockholder or
Representative from taking any action, after having notified DHI thereof, or
omitting to take any action, solely as a member of the Board of Directors of the
Company required so as not to violate such Stockholder's or Representative's
fiduciary obligations as a director of the Company after consultation with
outside counsel.

                  SECTION 1.7. Termination of Registration Rights Agreement.
Contingent upon the consummation of the Merger and effective as of the Effective
Time, the Stockholders hereby terminate, and waive any rights in respect of, the
Registration Rights Agreement, dated as of April 3, 2001, among the Company and
the Stockholders signatory thereto, which termination and waiver shall be
effective without any further action by the parties thereto.
<PAGE>

                  SECTION 1.8. Termination Agreement and Mutual Release. On the
Closing Date, each Stockholder and DHI shall execute and deliver the termination
agreement and mutual release contemplated by Section 6.14 of the Merger
Agreement.

                  SECTION 1.9. Section 341(f) Consent. Notwithstanding any
rights to the contrary set forth in Section 6.13 of the Reorganization
Agreement, each Stockholder hereby agrees that it will not request the Company
to file a statement with the IRS consenting to the application to the Company of
Section 341(f) of the Code except for a request made to the Company to file such
a statement immediately prior to the Merger as contemplated in Section 5.4 of
the Merger Agreement.

                                   ARTICLE II.

               REPRESENTATIONS AND WARRANTIES OF THE STOCKHOLDERS

                  Each Stockholder hereby represents and warrants to DHI as
follows:

                  SECTION 2.1. Due Authorization, Enforceability. Such
Stockholder has all requisite power and authority to execute, deliver and
perform this Agreement, to appoint DHI as its Proxy and to consummate the
transactions contemplated hereby. The execution, delivery and performance of
this Agreement, the appointment of DHI as such Stockholder's Proxy and the
consummation of the transactions contemplated hereby have been duly authorized
by all necessary action on the part of Stockholder. This Agreement has been duly
executed and delivered by or on behalf of such Stockholder and constitutes a
legal, valid and binding obligation of such Stockholder, enforceable against
such Stockholder in accordance with its terms, except as enforcement may be
limited by bankruptcy, insolvency, moratorium or other similar laws and except
that the availability of equitable remedies, including specific performance, is
subject to the discretion of the court before which any proceeding for such
remedy may be brought. There is no beneficiary or holder of a voting trust
certificate or other interest of any trust of which such Stockholder is trustee
whose consent is required for the execution and delivery of this Agreement or
the consummation by such Stockholder of the transactions contemplated hereby.

                  SECTION 2.2.  No Conflicts; Required Filings and Consents.

                  (a) The execution and delivery of this Agreement by such
Stockholder does not, and the performance of this Agreement by such Stockholder
will not, (i) conflict with or violate any trust agreement or other similar
documents relating to any trust of which such Stockholder is trustee, (ii)
conflict with or violate any law, rule, regulation, order, judgment or decree
applicable to such Stockholder or by which such Stockholder or any of such
Stockholder's properties is bound or affected or (iii) result in any breach of
or constitute a default (or an event that with notice or lapse of time or both
would become a default) under, or give to others any rights of termination,
acceleration or cancellation of, or result in the creation of a lien or
encumbrance on any assets of such Stockholder, including such Stockholder's
Subject Shares, pursuant to, any note, bond, mortgage, indenture, contract,
agreement, lease, license, permit, franchise or other instrument or obligation
to which such Stockholder is a party or by which such Stockholder or any of such
Stockholder's assets is bound or affected, except, in the case of

<PAGE>

clauses (ii) and (iii), for any such breaches, defaults or other occurrences
that would not prevent or delay the performance by such Stockholder of such
Stockholder's obligations under this Agreement.

                  (b) The execution and delivery of this Agreement by such
Stockholder does not, and the performance of this Agreement by such Stockholder
will not, require any consent, approval, authorization or permit of, or filing
with or notification to, any governmental or regulatory authority (other than
any necessary filing under the Exchange Act), domestic or foreign, except where
the failure to obtain such consents, approvals, authorizations or permits, or to
make such filings or notifications, would not prevent or delay the performance
by such Stockholder of such Stockholder's obligations under this Agreement.

                  SECTION 2.3. Title to Shares. Such Stockholder is the sole
record or beneficial owner of its Subject Shares, free and clear of any pledge,
lien, security interest, mortgage, charge, claim, equity, option, proxy, voting
restriction, voting trust or agreement, understanding, arrangement, right of
first refusal, limitation on disposition, adverse claim of ownership or use or
encumbrance of any kind ("Encumbrances"), other than as set forth on Schedule
1.2 and other than restrictions imposed by the securities laws or pursuant to
this Agreement and the Merger Agreement. Such Stockholder has the sole right and
power to vote and dispose of such Stockholder's Subject Shares.

                                  ARTICLE III.

                                  MISCELLANEOUS

                  SECTION 3.1. Definitions. Terms used but not otherwise defined
in this Agreement have the meanings ascribed to such terms in the Merger
Agreement.

                  SECTION 3.2. Termination. As used herein, "Term" means the
period beginning on the date hereof and ending on the date this Agreement shall
be terminated in accordance with its terms. This Agreement shall terminate and
be of no further force and effect (i) by the written mutual consent of the
parties hereto, (ii) upon termination of the Merger Agreement, including a
termination of the Merger Agreement pursuant to Section 7.1(d) thereof, in
accordance with its terms, or (iii) automatically and without any required
action of the parties hereto upon the Effective Time. No such termination of
this Agreement shall relieve any party hereto from any liability for any breach
of this Agreement prior to termination.

                  SECTION 3.3. Further Assurance. From time to time, at another
party's request and without consideration, each party hereto shall execute and
deliver such additional documents and take all such further action as may be
necessary or desirable to consummate and make effective, in the most expeditious
manner practicable, the transactions contemplated by this Agreement.

                  SECTION 3.4. Certain Events. Each Stockholder agrees that this
Agreement and such Stockholder's obligations hereunder shall attach to such
Stockholder's Subject Shares and shall be binding upon any person or entity to
which legal or beneficial ownership of such Subject Shares shall pass, whether
by operation of law or otherwise, including such Stockholder's heirs,

<PAGE>

guardians, administrators, or successors. Notwithstanding any transfer of
Subject Shares, the transferor shall remain liable for the performance of all
its obligations under this Agreement.

                  SECTION 3.5. No Waiver. The failure of any party hereto to
exercise any right, power, or remedy provided under this agreement or otherwise
available in respect hereof at law or in equity, or to insist upon compliance by
any other party hereto with its obligations hereunder, any custom or practice of
the parties at variance with the terms hereof shall not constitute a waiver by
such party of its right to exercise any such or other right, power or remedy or
to demand such compliance.

                  SECTION 3.6. Specific Performance. Each Stockholder
acknowledges that if such Stockholder fails to perform any of its obligations
under this Agreement immediate and irreparable harm or injury would be caused to
DHI for which money damages would not be an adequate remedy. In such event, each
Stockholder agrees that DHI shall have the right, in addition to any other
rights it may have, to specific performance of this Agreement. Accordingly, if
DHI should institute an action or proceeding seeking specific enforcement of the
provisions hereof, each Stockholder hereby waives the claim or defense that DHI,
as the case may be, has an adequate remedy at law and hereby agrees not to
assert in any such action or proceeding the claim or defense that such a remedy
at law exists. Each Stockholder further agrees to waive any requirements for the
securing or posting of any bond in connection with obtaining any such equitable
relief.

                  SECTION 3.7. Notice. All notices and other communications
given or made pursuant hereto shall be in writing and shall be deemed to have
been duly given or made if and when delivered personally or by overnight courier
to the parties at the following addresses or sent by electronic transmission,
with confirmation received, to the telecopy numbers specified below (or at such
other address or telecopy number for a party as shall be specified by like
notice):

                  (a)      If to DHI:

                           D.R. Horton,Inc.
                           1901 Ascension Blvd., Suite 100
                           Arlington, Texas  76006
                           Facsimile:  (817) 436-6053 and (817) 856-8252
                           Telephone: (817) 856-8200
                           Attention:  Rick Beckwitt and Ted Harbour

                   (b)     If to a Stockholder, at the address set forth below
such Stockholder's name on Schedule I.

                  SECTION 3.8. Expenses. Except as otherwise expressly set forth
herein, all fees, costs and expenses incurred in connection with this Agreement
and the transactions contemplated hereby shall be paid by the party incurring
such fees, costs and expenses.

                  SECTION 3.9. Headings. The headings contained in this
Agreement are for reference purposes only and shall not affect in any way the
meaning or interpretation of this Agreement. When a reference is made in this
Agreement to Sections or Schedules, such

<PAGE>

reference shall be to a section or schedule of this Agreement unless otherwise
indicated. Wherever the words "includes," "include" or "including" are used in
this Agreement, they shall be deemed to be followed by the words "without
limitation."

                  SECTION 3.10. Severability. If any term or other provision of
this Agreement is invalid, illegal or incapable of being enforced by any rule of
law, or public policy, all other conditions and provisions of this Agreement
shall nevertheless remain in full force and effect so long as the economic or
legal substance of the transactions contemplated hereby is not affected in any
manner adverse to any party. Upon such determination that any term or other
provision is invalid, illegal or incapable of being enforced, the parties hereto
shall negotiate in good faith to modify this Agreement so as to effect the
original intent of the parties as closely as possible in an acceptable manner to
the end that transactions contemplated hereby are fulfilled to the maximum
extent possible.

                  SECTION 3.11. Entire Agreement; No Third-Party Beneficiaries.
This Agreement constitutes the entire agreement and supersedes any and all other
prior agreements and undertakings, both written and oral, among the parties, or
any of them, with respect to the subject matter hereof, and this Agreement is
not intended to confer upon any other person any rights or remedies hereunder.

                  SECTION 3.12. Assignment. This Agreement shall not be assigned
by operation of law or otherwise.

                  SECTION 3.13. Governing Law. This Agreement shall be governed
by, and construed in accordance with, the laws of the State of Delaware
applicable to contracts executed in and to be performed entirely within that
State without regard to the principles of conflicts of law that would apply any
other law.

                  SECTION 3.14. Jurisdiction. Each party hereby irrevocably
submits to the exclusive jurisdiction of the Court of Chancery in the State of
Delaware in any action, suit or proceeding arising in connection with this
Agreement, and agrees that any such action, suit or proceeding shall be brought
only in such court (and waives any objection based on forum non conveniens or
any other objection to venue therein); provided, however, that such consent to
jurisdiction is solely for the purpose referred to in this Section 3.15 and
shall not be deemed to be a general submission to the jurisdiction of said Court
or in the State of Delaware other than for such purposes. Each party hereto
hereby waives any right to trial by jury in connection with any such action,
suit or proceeding.

                  SECTION 3.15. Amendment. This Agreement may not be amended
except by an instrument in writing signed by the parties hereto.

                  SECTION 3.16. Waiver. Any party hereto may (a) extend the time
for the performance of any of the obligations or other acts of the other parties
hereto, (b) waive any inaccuracies in the representations and warranties of the
other parties hereto contained herein or in any document delivered pursuant
hereto and (c) waive compliance by the other parties hereto with any of their
agreements or conditions contained herein. Any agreement on the part of a party
hereto to any such extension or waiver shall be valid only as against such party
and only if

<PAGE>

set forth in an instrument in writing signed by such party. The failure of any
party hereto to assert any of its rights under this Agreement or otherwise shall
not constitute a waiver of those rights.

                  SECTION 3.17. Counterparts. This Agreement may be executed in
one or more counterparts, and by the different parties hereto in separate
counterparts, each of which when executed shall be deemed to be an original but
all of which shall constitute one and the same agreement.

                            [SIGNATURES ON NEXT PAGE]

<PAGE>

                  IN WITNESS WHEREOF, DHI and the Stockholders have caused this
Agreement to be executed as of the date first written above.

                                      D.R. HORTON,INC.

                                      By:     /s/ DONALD R. HORTON
                                              ---------------------------------
                                              Donald R. Horton
                                              Chairman of the Board

                                      CLASS A STOCKHOLDERS:

                                      THE JAMES AND PATRICIA SCHULER FOUNDATION

                                      By:     /s/ JAMES K. SCHULER
                                              ---------------------------------

                                      JAMES K. SCHULER,
                                      as trustee for the James K. Schuler 1998
                                      Qualified Annuity Trust and the James K.
                                      Schuler Revocable Living Trust

                                               /s/ JAMES K. SCHULER
                                               ---------------------------------
                                               James K. Schuler

<PAGE>

                                      CLASS B STOCKHOLDERS:

                                      WPH-SCHULER LLC
                                      By each of its members

                                               APOLLO REAL ESTATE
                                               INVESTMENT FUND, L.P.

                                               By:      APOLLO REAL ESTATE
                                                        ADVISORS, L.P.
                                                        Its General Partner

                                               By:      APOLLO REAL ESTATE
                                                        MANAGEMENT, INC.
                                                        Its General Partner

                                               By:      /s/ MICHAEL D. WEAVER
                                                        ------------------------

                                               HIGHRIDGE PACIFIC HOUSING
                                               INVESTORS, L.P.

                                               By:      WPH ACQUISITIONS, INC.
                                                        Its General Partner

                                               By:      /s/
                                                        ------------------------
                                               Name:
                                                        ------------------------
                                               Title:
                                                        ------------------------

                                               BLACKACRE WPH, LLC

                                               By:      BLACKACRE CAPITAL
                                                        GROUP, L.P.
                                                        Its Managing Member

                                               By:      BLACKACRE CAPITAL
                                                        MANAGEMENT, CORP.
                                                        Its General Partner

                                               By:      /s/
                                                        ------------------------
                                               Name:
                                                        ------------------------
                                               Title:
                                                        ------------------------

<PAGE>

                                      APOLLO REAL ESTATE INVESTMENT FUND, L.P.
                                      In its individual capacity

                                      By:      APOLLO REAL ESTATE
                                               ADVISORS, L.P.
                                               Its General Partner

                                      By:      APOLLO REAL ESTATE
                                               MANAGEMENT, INC.
                                               Its General Partner

                                      By:      /s/ MICHAEL D. WEAVER
                                               ---------------------------------
                                               Michael D. Weaver
                                               Vice President

                                      HIGHRIDGE PACIFIC HOUSING INVESTORS, L.P.
                                      In its individual capacity

                                      By:      WPH ACQUISITIONS, INC.
                                               Its General Partner

                                      By:      /s/
                                               ---------------------------------
                                      Name:
                                               ---------------------------------
                                      Title:
                                               ---------------------------------

                                      BLACKACRE WPH, LLC
                                      In its individual capacity

                                      By:      BLACKACRE CAPITAL
                                               GROUP, L.P.
                                               Its Managing Member

                                      By:      BLACKACRE CAPITAL
                                               MANAGEMENT, CORP.
                                               Its General Partner

                                      By:      /s/
                                               ---------------------------------
                                      Name:
                                               ---------------------------------
                                      Title:
                                               ---------------------------------

<PAGE>

                                   SCHEDULE I

<Table>
<Caption>
                                                    Total Number of Shares Owned
Name and Address of Stockholder                               of Record                      Subject Shares
------------------------------------------------- ---------------------------------- --------------------------------
<S>                                               <C>                                <C>
The James And Patricia Schuler Foundation                  500,000 Class A                   250,000 Class A
828 Fort Street Mall, Fourth Floor
Honolulu, HI  96813

The James K. Schuler 1998 Qualified Annuity                314,065 Class A                   157,033 Class A
Trust
828 Fort Street Mall, Fourth Floor
Honolulu, HI  96813

The James K. Schuler Revocable Living Trust               9,619,763 Class A                4,809,881 Class A
828 Fort Street Mall, Fourth Floor
Honolulu, HI  96813

WPH-Schuler, LLC                                         18,754,727 Class B                18,754,727 Class B
400 Continental Blvd., Suite 100
El Segundo, CA  90245

Apollo Real Estate Investment Fund, L.P.
2 Manhattanville Road                                         0 Class B                         0 Class B
Purchase, NY  10577-2118

Highridge Pacific Housing Investors, L.P.                     0 Class B                         0 Class B
300 Continental Blvd., Suite 360
El Segundo, CA  90245

Blackacre WPH, LLC                                            0 Class B                         0 Class B
450 Park Avenue, 28th Floor
New York, NY  10022
</Table>

<PAGE>

<Table>
<Caption>
                                                    Total Number of Shares Owned
Name and Address of Stockholder                               of Record                      Subject Shares
------------------------------------------------- ---------------------------------- --------------------------------
<S>                                               <C>                                <C>
The James And Patricia Schuler Foundation                 500,000 Class A                    250,000 Class A
828 Fort Street Mall, Fourth Floor
Honolulu, HI  96813

The James K. Schuler 1998 Qualified Annuity               314,065 Class A                    157,033 Class A
Trust
828 Fort Street Mall, Fourth Floor
Honolulu, HI  96813

The James K. Schuler Revocable Living Trust              9,619,763 Class A                  4,809,881 Class A
828 Fort Street Mall, Fourth Floor
Honolulu, HI  96813

WPH-Schuler, LLC                                         18,754,727 Class B                18,754,727 Class B
400 Continental Blvd., Suite 100
El Segundo, CA  90245

Apollo Real Estate Investment Fund, L.P.
2 Manhattanville Road                                  9,356,136 Class B (1)              9,356,136 Class B (1)
Purchase, NY  10577-2118

Highridge Pacific Housing Investors, L.P.               7,076,360 Class B(1)              7,076,360 Class B(1)
300 Continental Blvd., Suite 360
El Segundo, CA  90245

Blackacre WPH, LLC                                      2,322,232 Class B(1)              2,322,232 Class B(1)
450 Park Avenue, 28th Floor
New York, NY  10022
</Table>

(1) The beneficial ownership of these entities is based entirely on assumptions
being made as of the date hereof. The actual beneficial ownership of each entity
on the date of the Company's stockholder meeting and on the Closing Date will be
calculated according to the provisions set forth in the amended and restated
operating agreement of WPH-Schuler, LLC.

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