EXHIBIT 10.1

STANDARD INDUSTRIAL LEASE
OPTION EXERCISE

     This Exercise of Option is made with respect to that certain Standard
Industrial Lease dated February 18, 1991 (the “Lease”) between 5700 West 96th
Street, a California general partnership (“Lessor”), and Diagnostic Products
Corporation, a California corporation (“Lessee”), as amended pursuant to that
certain Second Addendum to Standard Industrial Lease between Lessor and Lessee
dated April 1, 2002 (the “Addendum”).

     WHEREAS, pursuant to the Addendum, Lessee has an option to extend the Lease
through December 31, 2006 by providing written notice to the Lessor no later
than November 1, 2004 (the “Option”); and

     WHEREAS, the parties acknowledge a mistake in the Addendum with respect to
the Option term provided in paragraph 20 of the Addendum and the date by which
notice must be given to exercise the Option in paragraph 22 of the Addendum; and

     WHEREAS, Lessor orally extended the period of time Lessee had the right to
exercise the Option; and

     WHEREAS, Lessee desires to exercise the Option;

     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties agree as follows:

     1. Paragraph 20 of the Addendum is hereby reformed and clarified to read in
full as follows:

“Lessee extends the lease for a period of two years beginning on January 1, 2003
and ending on December 31, 2004.”

     2. Paragraph 22 of the Addendum is hereby reformed and clarified to read in
full as follows:

“Lessee shall have an option to extend the lease an additional two years beyond
December 31, 2004 at a rent per month of $90,562 by providing notice to the
Partnership not later than November 1, 2004.”

 

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     3. Lessee hereby exercises the Option to extend the Lease for the period
January 1, 2005 through December 31, 2006 at a rent per month of $90,562,
effective as of January 1, 2005, and Lessor consents to such exercise.

              Dated as of January 1, 2005   DIAGNOSTIC PRODUCTS CORPORATION    
 
           

  By   /S/ James L. Brill    

           

      James L. Brill, Vice President, Finance    
 
           
 
                5700 WEST 96TH STREET, a general partnership    
 
           

  By   /S/ Michael Ziering    

           

      Michael Ziering, Partner    

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