Exelixis, Inc. today announced its joint venture with Bayer's crop protection business group, Genoptera LLC, delivered two assays for high- throughput screening to Bayer. The delivery of these assays triggers undisclosed milestone payments to Exelixis.

The delivered assays are designed to identify novel classes of safe and effective insecticides. Bayer scientists will screen the assays against their extensive compound collection to identify leads for further development. Exelixis will receive additional milestone payments as the projects move forward and royalty payments on marketed products.

"Bayer is a leader in the development of safe and effective pesticides, and through the Genoptera
joint venture, we expect to add substantially to our insecticide pipeline,'' said Detlef Wollweber,
Ph.D., head of research, crop protection of Bayer AG. "Over the course of the relationship, we
look forward to receiving an increasing stream of assays for our high throughput screening facility.''

"We are extremely pleased with the rapid progress from target to assay development from the
Genoptera team, which directly results from our close working relationship with the Bayer team,''
stated George A. Scangos, Ph.D., president and chief executive officer of Exelixis, Inc. "The
nature of this collaboration allows Exelixis to combine its expertise in model system genetics and
comparative genomics with Bayer's expertise to develop and commercialize innovative
insecticides.''

Genoptera LLC was formed in January 2000 to discover novel insecticides and nematicides. The
joint venture is a continuation and expansion of the collaboration that Exelixis and Bayer initially
established in April 1998 and expanded in June 1999. In addition to $80 million in committed
research funding over the course of the eight year joint venture, the arrangement involves a $20
million up-front payment and performance-based milestone and royalty payments from Genoptera
to Exelixis. Bayer has the exclusive right to commercialize insecticides based on technology
developed by Genoptera.

Bayer is a diversified, international chemicals and health care group, offering a wide variety of
products and services from its Health Care, Agriculture, Polymers and Chemicals business
segments. In 1999, Bayer employed a worldwide workforce of 120,000 and recorded sales of
EUR 27.32 billion.

Exelixis, Inc. is a leading biotechnology company focused on the life sciences industries and
development through its expertise in comparative genomics and model system genetics. These
technologies provide a rapid, efficient and cost-effective way to move from DNA sequence data to
knowledge about the function of genes and the proteins that they encode. The company's
technology is broadly applicable to all life science industries including pharmaceutical, diagnostic, agricultural biotechnology and animal health. Exelixis has partnerships with Bayer, Pharmacia, Bristol-Myers Squibb and Dow AgroSciences and is building its internal development program in the area of oncology.

Exelixis and the Exelixis logo are registered U.S. trademarks. 

Company news release
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