AFFX Affymetrix, Inc.

Affymetrix Inc. (Nasdaq:AFFX) and PathWork Informatics Inc. announced today that Affymetrix has granted PathWork long-term non-exclusive access to its microarray technology to develop and market in-vitro diagnostic tests for cancer. Under the agreement, PathWork has the right to use Affymetrix microarray technology for the development of tests for cancer of unknown primary, as well as the option to develop other cancer tests. The resulting microarray products would enable clinicians to provide more efficient and complete methods to diagnose, classify and manage cancer. The collaboration, reached under the Powered by Affymetrix(TM) program, allows PathWork to incorporate Affymetrix' patented arrays into PathWork Oncology Suites, the company's diagnostic kits currently under development. PathWork is creating next-generation cancer diagnostics that help oncologists make accurate diagnoses, informed prognoses, and optimal treatment decisions for their patients. The company's first three product candidates focus on metastatic tumors, as well as prostate cancer and colon cancer. "This agreement marks an important milestone for PathWork, allowing us to focus on leveraging our proprietary technology for discovering high-performance, gene expression-based diagnostic tests," said Glenda Anderson, CEO of PathWork Informatics. "Affymetrix' technology provides a proven microarray platform for our kits, and its widespread use makes this collaboration a natural choice for PathWork." "Microarray-based tools and applications are accelerating the discovery and implementation of clinical oncology diagnostics in this era of molecular medicine," said Robert Lipshutz, Ph.D., Senior Vice President Molecular Diagnostics and Emerging Markets at Affymetrix. "We are pleased that PathWork chose Affymetrix technology and believe that the growing Powered by Affymetrix program continues to demonstrate that the innovators in the diagnostic field are adopting our proven technology platform." Under the Powered by Affymetrix program, companies license technology from Affymetrix to develop innovative microarray products. This includes the GeneChip(R) System 3000Dx (GCS3000Dx), the first microarray instrumentation system for molecular diagnostic laboratories. The GCS3000Dx has been granted regulatory clearance by the U.S. Food and Drug Administration and is CE marked in the European Union for in-vitro diagnostic use. The custom-designed technology is being used in many applications, including clinical diagnostics, forensics, animal, industrial and food testing. About Affymetrix: Affymetrix scientists invented the world's first high-density microarray in 1989 and began selling the first commercial microarray in 1994. Since then, Affymetrix GeneChip(R) technology has become the industry standard in molecular biology research. Affymetrix technology is used by the world's top pharmaceutical, diagnostic and biotechnology companies as well as leading academic, government and not-for-profit research institutes. More than 1,300 systems have been installed around the world and nearly 3,000 peer-reviewed papers have been published using the technology. Affymetrix' patented photolithographic manufacturing process provides the most information capacity available today on an array, enabling researchers to use a whole-genome approach to analyzing the relationship between genetics and health. Affymetrix is headquartered in Santa Clara, Calif., with manufacturing facilities in Sacramento, Calif., and Bedford, Mass. The company maintains important sales and marketing operations in Europe and Asia and has about 1,000 employees worldwide. For more information about Affymetrix, please visit the company's website at www.Affymetrix.com. About PathWork Informatics: PathWork Informatics has developed proprietary systems for high-throughput discovery of genomic diagnostics. PathWork technologies have shown promise in identifying cancer site of origin, classifying leukemia and predicting breast cancer recurrence. PathWork is now working to obtain FDA clearance of its first product. The company will continue to expand its product pipeline through partnerships with researchers and cancer centers worldwide. PathWork is headquartered in San Jose, Calif. For more information about PathWork, please visit the company's website at www.pathworkinfo.com. All statements in this press release that are not historical are "forward-looking statements" within the meaning of Section 21E of the Securities Exchange Act as amended, including statements regarding Affymetrix' "expectations," "beliefs," "hopes," "intentions," "strategies" or the like. Such statements are subject to risks and uncertainties that could cause actual results to differ materially for Affymetrix from those projected, including, but not limited to: risks of the Company's ability to achieve and sustain higher levels of revenue, higher gross margins, reduced operating expenses; uncertainties relating to technological approaches, manufacturing (including risks related to the Company's ability to achieve hoped-for manufacturing yields for certain array products, including the ability to identify and resolve manufacturing problems), product development (including uncertainties relating to commercial and technological success of the strategic alliance between PathWork Informatics and Affymetrix discussed in this press release); personnel retention; uncertainties related to cost and pricing of Affymetrix products; dependence on collaborative partners; uncertainties relating to sole source suppliers; uncertainties relating to FDA and other regulatory approvals; competition; risks relating to intellectual property of others and the uncertainties of patent protection and litigation. These and other risk factors are discussed in Affymetrix' Form 10-K for the year ended December 31, 2004 and other SEC reports, including its Quarterly Reports on Form 10-Q for subsequent quarterly periods. Affymetrix expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in Affymetrix' expectations with regard thereto or any change in events, conditions, or circumstances on which any such statements are based. NOTE: Affymetrix, the Affymetrix logo, and GeneChip are registered trademarks owned or used by Affymetrix Inc.