ST. LOUIS, June 19 — Sigma-Aldrich (Nasdaq:SIAL) today announced it has entered into a five-year collaboration to develop optimal cell lines for the production of monoclonal antibodies. Scientists at the University of California, San Francisco will lead the research into antibodies for a variety of cancer targets, autoimmune diseases, stem cell characteristics and commonly neglected disease targets. Under the terms of the agreement, research targets will be determined by a steering committee composed of leading scientists at UCSF, including Lewis Lanier, Ph.D. Professor and Vice Chair, Department of Microbiology & Immunology; Jeffrey Bluestone, Ph.D. Director, UCSF Diabetes Center; and Susan Fisher, Ph.D. Professor, Department of Cell & Tissue Biology. The committee will direct research into antibodies for cancer targets, stem cell surface markers and autoimmune disease targets. The University will have free access to the antibodies resulting from the partnership for its ongoing immunology and disease research.

“Sigma-Aldrich is committed to developing the most comprehensive and highly validated collection of monoclonal antibodies available for the cell biology research community,” said Dr. David Smoller, President of Sigma-Aldrich’s Research Biotech Business Unit. “By partnering with the highly regarded UCSF research team, Sigma-Aldrich is helping to further promote the study of a number of important cancer targets, regenerative medicine applications and neglected diseases.”

Sigma-Aldrich is expanding its antibody content offering as part of its plan to become a leading developer and manufacturer of the next generation of monoclonal antibody products for life science researchers. Earlier this year, the company announced a partnership to distribute the

highly-validated Prestige antibodies powered by Atlas Antibodies, the commercial arm of the Human Proteome Resource. Sigma-Aldrich is also collaborating with AbD Serotec, a Division of MorphoSys, to design, produce and distribute unique recombinant research antibodies using MorphoSys’s proprietary HuCAL GOLD technology.

For more information on Sigma-Aldrich’s extensive monoclonal antibody product portfolio, visit the company’s interactive Antibody Explorer catalog at http://www.sigmaaldrich.com/antibody.

About Sigma-Aldrich: Sigma-Aldrich is a leading Life Science and High Technology company. Our biochemical and organic chemical products and kits are used in scientific and genomic research, biotechnology, pharmaceutical development, the diagnosis of disease and as key components in pharmaceutical and other high technology manufacturing. We have customers in life science companies, university and government institutions, hospitals, and in industry. Over one million scientists and technologists use our products. Sigma-Aldrich operates in 36 countries and has 7,900 employees providing excellent service worldwide. Sigma-Aldrich is committed to Accelerating Customer Success through Leadership in Life Science, High Technology and Service.

For more information about Sigma-Aldrich, please visit our award-winning website at http://www.sigma-aldrich.com. About UCSF: UCSF is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. Cautionary Statement: This release contains forward-looking statements relating to future performance, goals, strategic actions and initiatives and similar intentions and beliefs and other statements regarding the Company’s expectations, goals, beliefs, intentions and the like, which involve assumptions regarding the Company’s operations and conditions in the markets the Company serves. The Company does not undertake any obligation to update these forward-looking statements.

UC Disclaimer: The information stated above was prepared by Sigma-Aldrich to report a research collaboration and reflects solely the opinion of Sigma-Aldrich. Nothing in this statement shall be construed to imply any support or endorsement of Sigma-Aldrich, or any of its products, by The Regents of the University of California, its officers, agents and employees.