Eisai Co., Ltd. Licenses the Elucidator(R) Protein Expression Data Analysis System from Rosetta Biosoftware.

SEATTLE & TOKYO -- Rosetta Biosoftware announced today that Eisai Co., Ltd. licensed the Elucidator[R] system for differential protein expression analysis and biomarker discovery. Eisai Co., one of the largest pharmaceutical companies in Japan, will be using the Elucidator system in the Laboratory of Seeds Finding Technology to support LC-MS quantification methods for identifying potential neurology biomarkers.

"The Elucidator system will be an important tool for enabling quantitative methods and characterizing cancer proteomes by multidimensional LC-MS/MS," said Yoshiya Oda, Ph.D., senior scientist at the Laboratory of Seeds Finding Technology.

"We are honored to provide the Elucidator system to this prestigious pharmaceutical company," said Yelena Shevelenko, vice president and general manager of Rosetta Biosoftware. "The Elucidator system supports end-to-end data management and analysis workflow for comparative proteomics, and provides multiple ways for scientists to analyze and refine their data to achieve high-confidence results."

About Eisai Co., Ltd.

Eisai (Headquarters: Tokyo; President & CEO: Haruo Naito) is a Human Healthcare Corporation striving for innovative solutions in prevention, cure, and care for the health and well-being of people worldwide. We combine our talents to understand and meet the needs of patients and their families to enhance the quality of life. For more information, visit www.eisai.co.jp/index.html.

About the Rosetta Elucidator System

The Elucidator system's advanced data management capabilities allow users to effectively organize, search for, and retrieve raw and processed protein expression data. The application serves as a core integrator for proteomics research by working directly with select instrument APIs, sample annotation systems, and common protein ID search engines. In addition, it provides a suite of advanced statistical analysis and visualization tools for data mining and discovery of potential protein biomarkers and proteins that are differentially expressed among different phenotypes or drug treatments. The Elucidator system combines these data management and analysis capabilities with the flexibility of a highly customizable environment: users can incorporate organization-specific workflows into customized visual scripts that leverage Elucidator system statistical tools and customer-proprietary algorithms, as well as those available in the public domain. The Rosetta Elucidator product line is designed to meet the needs of both large and small organizations.

Additional information about the Rosetta Elucidator system can be found on the Rosetta Biosoftware Web site at www.rosettabio.com.

About Rosetta Biosoftware

Rosetta Biosoftware is a leading provider of informatics solutions for life science research. Its comprehensive software solutions, including the Rosetta Resolver and Rosetta Elucidator systems, empower life scientists with advanced, scalable, and easy-to-use analysis platforms that accelerate discovery research. Rosetta Biosoftware is a business unit of Rosetta Inpharmatics LLC, a wholly owned subsidiary of Merck & Co., Inc. (NYSE: MRK). More information about Rosetta Biosoftware is available at www.rosettabio.com.

Forward-Looking Statements

This press release contains "forward-looking statements" as that term is defined in the Private Securities Litigation Reform Act of 1995. These statements involve risks and uncertainties, which may cause results to differ materially from those set forth in the statements. The forward-looking statements may include statements regarding product development, product potential, or financial performance. No forward-looking statement can be guaranteed, and actual results may differ materially from those projected. Neither Rosetta Inpharmatics nor Merck & Co., Inc. undertakes any obligation to publicly update any forward-looking statement, whether as a result of new information, future events, or otherwise. Forward-looking statements in this press release should be evaluated together with the many uncertainties that affect the business of Merck & Co., Inc. including, among others, the extent to which Rosetta Inpharmatics' technology platform can be used in drug discovery programs, uncertainty of market acceptance of Rosetta Inpharmatics' technologies, ability to compete against existing technologies, and those mentioned in the cautionary statements in Item 1 of Merck's Form 10-K for the year ended Dec. 31, 2005, and in its periodic reports on Form 10-Q and Form 8-K (if any) which are incorporated by reference.

Rosetta Resolver and Elucidator are U.S. registered trademarks of Rosetta Inpharmatics LLC.