FRAMINGHAM, MA – February 23, 2009 -- GTC Biotherapeutics, Inc. ("GTC", Nasdaq: GTCB) has entered into an agreement with JCOM Co. Ltd. in the Republic of Korea to provide a license for the transgenic development of recombinant human insulin products in Asia. Under the agreement, GTC will establish the appropriate cell lines and demonstrate production over the next 12 months. JCOM has the option for exclusive marketing rights in Asia. JCOM will compensate GTC for successful development of the transgenic production system as well as a license fee. JCOM will also pay GTC a royalty on any commercial sales of the products. The agreement contemplates JCOM’s establishment of a transgenic production system for recombinant human insulin products in the Republic of Korea.

“We are pleased to enable JCOM to pursue the development of insulin products utilizing our first-in-class transgenic technology platform for the production of human therapeutic proteins,” stated Geoffrey F. Cox, PhD, GTC’s Chairman and CEO.

Insulin is a protein produced in the pancreas that controls glucose levels in the bloodstream. Recombinant insulin products are used to manage diabetes.

JCOM Co. LTD is a biotechnology company specializing in cloning and stem cell research. JCOM is affiliated with Dong-A Pharmaceutical, one of Korea’s leading research-based pharmaceutical and healthcare companies. Dong-A has a growing pipeline of biopharmaceutical products.

GTC Biotherapeutics develops, supplies, and commercializes therapeutic proteins produced through transgenic animal technology. ATryn®, GTC’s recombinant human antithrombin, has been approved for use in the United States and Europe. ATryn® is the first and only transgenically produced product to be approved for therapeutic use anywhere in the world. In addition to ATryn®, GTC is developing a portfolio of recombinant human plasma proteins with known therapeutic properties. These proteins include recombinant forms of human coagulation factors VIIa, VIII, and IX, which are being developed for the treatment of hemophilia, and alpha-1 antitrypsin. GTC also has a monoclonal antibody portfolio that includes a monoclonal antibody to CD20 and a monoclonal antibody to CD137. GTC’s intellectual property includes a patent in the United States through 2021 for the production of any therapeutic protein in the milk of any transgenic mammal. GTC’s transgenic production platform is particularly well suited to enabling cost effective development of proteins that are difficult to express in traditional recombinant production systems as well as proteins that are required in large volumes. Additional information is available on the GTC web site, http://www.gtc-bio.com.

This press release contains forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding the potential commercial development of recombinant insulin products by JCOM. Such forward-looking statements are subject to a number of risks, uncertainties and other factors that could cause actual results to differ materially from future results expressed or implied by such statements. Factors that may cause such differences include, but are not limited to, the risks and uncertainties discussed in GTC's most recent Annual Report on Form 10-K and its other periodic reports filed with the Securities and Exchange Commission, including the uncertainties associated with conducting clinical studies, and the risks and uncertainties associated with dependence upon the actions of collaboration partners and regulatory agencies. GTC cautions investors not to place undue reliance on the forward-looking statements contained in this release. These statements speak only as of the date of this document, and GTC undertakes no obligation to update or revise the statements, except as may be required by law.