This announcement is for informational purposes only and does not constitute an offer to purchase or a solicitation of an offer to sell HGS common stock. The solicitation and offer to buy HGS common stock, commenced by GlaxoSmithKline plc through its wholly owned subsidiary, H. Acquisition Corp., have been made pursuant to an offer to purchase and related materials, filed on Schedule TO with the U.S. Securities and Exchange Commission (SEC), as amended and as will be further amended from time to time. In response to the offer, HGS has filed a solicitation/recommendation statement on Schedule 14D-9 with the SEC, as amended and as will be further amended from time to time. Investors and securityholders are urged to read these materials carefully since they contain important information, including the terms and conditions of the offer. Investors and security holders may obtain free copies of these materials and other documents filed by GSK and HGS with the SEC at the website maintained by the SEC as www.sec.gov. The offer to purchase and related materials may also be obtained for free by contacting the information agent for the tender offer, D.F. King & Co., Inc. at (212) 269-5550 or (800) 848-2998 (toll-free) or by email at HGStender@dfking.com. HGS will also provide a copy of the solicitation/recommendation statement materials without charge on its website at www.hgsi.com, or HGS stockholders may call HGS’ Information Agent, Innisfree M&A Incorporated, toll-free at 877-717-3926.