Richmond, California
March 18, 2003

Sangamo BioSciences, Inc. (Nasdaq: SGMO - News) today announced that it has been granted a United States patent entitled "Regulation of Endogenous Gene Expression in Cells Using Zinc Finger
Proteins." The patent includes claims covering the activation or repression of any endogenous gene in any cell type using zinc finger DNA-binding proteins. Similar patents have already issued in the United Kingdom and Australia and counterpart applications are pending worldwide.

"Our pioneering achievements in the regulation of endogenous genes with engineered zinc finger
DNA-binding protein transcription factors (ZFP TFs) are the basis for this fundamental patent that covers the regulation of any gene, in any cell type and confirms our technical and commercial leadership in this area," said Edward Lanphier, Sangamo's president and chief executive officer. "With the issuance of this patent we continue to advance our pre-eminent intellectual property position with respect to the regulation of gene expression using ZFP TFs. Although the sequences of many therapeutically relevant genes have been patented as isolated or purified sequences, a major advantage of Sangamo's unique technology is that it regulates endogenous cellular genes and is consequently independent of such patents."

Zinc finger DNA-binding proteins (ZFPs) are the dominant class of naturally occurring transcription factors in organisms from yeast to humans. Transcription factors, which are found in the nucleus of every cell, bind to DNA to regulate gene expression. Though there are many kinds of transcription factors, only zinc finger DNA-binding proteins are amenable to engineering and precise targeting to a particular gene or genes of interest. Since the over- expression or under-expression of individual genes is the basis for many diseases, the ability to regulate genes with engineered ZFPs has enormous potential therapeutic benefit.

The inventions covered by this patent (U.S. Patent No. 6,534,261) were made by Sangamo scientists. The patent covers methods for the activation or repression of endogenous genes, including human vascular endothelial growth factor (VEGF), a gene that plays a critical role in the formation of new blood vessels. Sangamo is currently investigating the use of ZFPs which activate VEGF as therapeutic agents for the treatment of cardiovascular disease.

Sangamo BioSciences, Inc., of Richmond, CA, is focused on the research and development of novel transcription factors for the regulation of gene expression. The company's most advanced therapeutic development program involves the use of transcription factors for the treatment of coronary artery disease and peripheral arterial disease. Other therapeutic development programs are focused on cancer and infectious diseases. Sangamo's proprietary technology enables the engineering of transcription factors known as zinc finger DNA-binding proteins, or ZFPs. By engineering ZFPs so that they can recognize a specific gene, Sangamo has created ZFP transcription factors (ZFP TFs) that can control gene expression and, consequently, cell function. The company is developing ZFP TFs as a fundamentally enabling technology for commercial applications in human therapeutics, pharmaceutical discovery and plant agriculture. Over twenty leading pharmaceutical and biotechnology
companies have utilized ZFP TFs.