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                                                                   Exhibit 10.87


                    ASSIGNMENT OF COMMERCIALIZATION AGREEMENT

      This is an Agreement, effective as of the 1st day of April, 1995 (the
EFFECTIVE DATE), among Coulter Pharmaceutical, Inc., a corporation incorporated
in the State of Delaware, with offices located at 550 California Avenue, Suite
200, Palo Alto, California 94306-1440 ("CPI"); Coulter Corporation, a
corporation incorporated in the State of Delaware, with offices located at 11800
S.W. 147 Avenue, Miami, Florida 33196 ("COULTER"); and the Regents of the
University of Michigan, a constitutional corporation of the State of Michigan,
with offices located at 3003 South State, Room 2071, Ann Arbor, Michigan
48109-1280 ("MICHIGAN"). CPI, COULTER and MICHIGAN agree as follows:

1.    BACKGROUND

1.1   MICHIGAN and COULTER have previously entered into a COMMERCIALIZATION
        AGREEMENT, attached hereto and incorporated herein as the Attachment,
        covering certain TECHNOLOGY and LICENSED PATENTS as therein defined.

1.2   COULTER wishes to assign all of its rights and obligations under the
        COMMERCIALIZATION AGREEMENT to CPI, and CPI wishes to accept such
        assignment. As required by the COMMERCIALIZATION AGREEMENT, and
        consistent with its mission of education and research, MICHIGAN wishes
        to consent to such assignment.

2.    ASSIGNMENT

2.1   COULTER hereby assigns all of its rights and obligations under the
        COMMERCIALIZATION AGREEMENT to CPI.

2.2   CPI hereby accepts this Assignment, all of the terms and conditions of the
        COMMERCIALIZATION AGREEMENT, and all of COULTER'S rights and obligations
        under the COMMERCIALIZATION AGREEMENT,

2.3   MICHIGAN hereby accepts this Assignment.

2.4   COULTER, CPI and MICHIGAN acknowledge that the parties to the
        COMMERCIALIZATION AGREEMENT henceforth are CPI and MICHIGAN. Obligations
        fully satisfied by COULTER, such as the license issue fee, shall be
        deemed performed by CPI.

2.5   COULTER'S rights and obligations under the COMMERCIALIZATION AGREEMENT
        shall be deemed to have been terminated in accordance Article 13, as if
        the COMMERCIALIZATION AGREEMENT had been voluntarily terminated by
        notice of COULTER according to Paragraph 13.4. If CPI thereafter
        terminates the COMMERCIALIZATION AGREEMENT for any reason under
        Paragraph 13.4, then MICHIGAN shall notify COULTER and COULTER shall be
        entitled, for 60 days following such notice, to assume the rights and
        obligations of CPI to the COMMERCIALIZATION AGREEMENT.
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      IN WITNESS WHEREOF, the PARTIES hereto have executed this Agreement in
duplicate originals by their duly authorized officers or representatives.

COULTER PHARMACEUTICAL, INC.       THE REGENTS OF THE UNIVERSITY OF MICHIGAN

/s/ ARNOLD ORONSKY                 /s/ ROBERT L. ROBB
-------------------------------    --------------------------------------------
Title: CEO                         Title: Director, Technology Management Office




COULTER CORPORATION


 /s/ SUE VAN
-------------------------------------
Chief Financial Officer and Treasurer