Maxygen, Inc., and Pioneer Hi-Bred International, Inc. today announced a major five-year strategic research collaboration. In this collaboration, Maxygen will exclusively apply its proprietary technology to generate novel gene products for Pioneer to use in the development of specific crop protection and quality grain traits in corn, soybeans, and other crops.

Under the terms of this agreement, in exchange for global commercialization rights, Pioneer will
make a $5 million equity investment in Maxygen and $2.5 million in initial payments. Pioneer
also will pay $27.5 million over five years for research and technology development. The
agreement also provides Maxygen with other possible payments of up to $50 million related to
commercial success.

"Maxygen has a unique combination of new technology and high-throughput screening that,
when combined with other technologies, will help us to develop improved genetics for our
customers,'' says Tony Cavalieri, vice president of Trait and Technology Development at
Pioneer. "The shuffling technology is a valuable component for capitalizing on the genes we've
discovered as a result of our early work in genomics.''

"Pioneer's aggressive integration of new technologies made them a perfect fit for us,'' said
Russell Howard, President and CEO of Maxygen. "They were the first agricultural company to
enter into genomics for product improvement and therefore, this agreement was a logical and
critical next step. We are also pleased to have consummated this collaboration as a part of our
business strategy to rapidly develop multiple high-value products in collaboration with the
world's leading companies in diverse industries.''

Pioneer Hi-Bred International, Inc.  is the world's leading supplier of agricultural genetics and is a leading developer and integrator of agricultural technology. Headquartered in Des Moines, Iowa, Pioneer develops, produces and markets a full line of seeds, forage/grain additives and services to farmers, grain processors, and other customers worldwide.

Maxygen, Inc. headquartered in Santa Clara, CA, was founded in a March 1997 spinout from
Glaxo Wellcome - Affymax, led by biotech entrepreneur Alejandro Zaffaroni. The Company is
the leader in nucleic acid recombination technologies for evolving new properties into single
genes, multi-gene systems, pathways, vectors and genomes. Maxygen is developing its
technologies to provide value to a broad range of applications including human therapeutics,
chemicals, vaccines, industrial enzymes and nutraceuticals. In addition to the Pioneer
collaboration, Maxygen has additional relationships with leading companies and research
agencies, including Novo Nordisk.

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