Lazard and Morgan Stanley are acting as financial advisors to GSK, and Cleary Gottlieb Steen & Hamilton and Wachtell, Lipton, Rosen & Katz are providing legal advice to the company. Goldman, Sachs & Co. and Credit Suisse Securities (USA) LLC are serving as financial advisors to HGS, and Skadden, Arps, Slate, Meagher & Flom LLP and DLA Piper LLP (US) are serving as legal counsel.GlaxoSmithKline – one of the world’s leading research-based pharmaceutical and healthcare companies – is committed to improving the quality of human life by enabling people to do more, feel better and live longer. For further information please visit www.gsk.com. Human Genome Sciences -- exists to place new therapies into the hands of those battling serious disease. For more information about HGS, please visit the Company’s web site at www.hgsi.com. HGS, Human Genome Sciences and BENLYSTA ® are trademarks of Human Genome Sciences, Inc. Other trademarks referenced are the property of their respective owners. Cautionary statement regarding forward-looking statements This communication contains forward-looking statements. GSK cautions readers that any forward-looking statements made by GSK, including those made in this communication, are subject to risks and uncertainties that may cause actual results to differ materially from those contained in the forward-looking statements. Such forward-looking statements include, but are not limited to, statements about the benefits of a business combination transaction involving GSK and HGS, including future financial and operating results, GSK’s plans, objectives, expectations (financial or otherwise) and intentions relating to the business combination and other statements that are not historical facts. Factors that may affect GSK’s operations are described under ‘Risk factors’ in the ‘Financial review & risk’ section in GSK’s Annual Report 2011 included as exhibit 15.2 to GSK’s Annual Report on Form 20-F for 2011. This announcement includes statements that are forward-looking. These forward-looking statements are based on HGS’s current intentions, beliefs and expectations regarding future events. HGS cannot guarantee that any forward-looking statement will be accurate. Investors should realize that if underlying assumptions prove inaccurate or unknown risks or uncertainties materialize, actual results could differ materially from HGS’s expectations. Investors are, therefore, cautioned not to place undue reliance on any forward-looking statement. Any forward-looking statement speaks only as of the date of this announcement, and, except as required by law, HGS does not undertake to update any forward-looking statement to reflect new information, events or circumstances. Some important factors that could cause HGS’s actual results to differ from its expectations in these forward-looking statements include: HGS’s lack of commercial experience and dependence on the sales growth of BENLYSTA; any failure to commercialize BENLYSTA successfully; the occurrence of adverse safety events with HGS’s products; changes in the availability of reimbursement for BENLYSTA; the inherent uncertainty of the timing, success of, and expense associated with, research, development, regulatory approval and commercialization of HGS’s pipeline products, including darapladib and albiglutide, and new indications for existing products; uncertainty as to the future success of darapladib and GSK’s ability to develop and commercialize darapladib; substantial competition in HGS’s industry, including from branded and generic products; the highly regulated nature of HGS’s business; uncertainty regarding HGS’s intellectual property rights and those of others; the ability to manufacture at appropriate scale, and in compliance with regulatory requirements, to meet market demand for HGS’s products; HGS’s substantial indebtedness and lease obligations; HGS’s dependence on collaborations over which it may not always have full control; foreign exchange rate valuations and fluctuations; the impact of HGS’s acquisitions and strategic transactions; changes in the health care industry in the U.S. and other countries, including government laws and regulations relating to sales and promotion, reimbursement and pricing generally; significant litigation adverse to HGS, including product liability and patent infringement claims; HGS’s ability to attract and retain key personnel; increased scrutiny of the health care industry by government agencies and state attorneys general resulting in investigations and prosecutions; risks and uncertainties associated with the merger agreement and related tender offer by GSK and; the outcome of any litigation related to the merger agreement and related tender offer by GSK. The foregoing list sets forth many, but not all, of the factors that could cause actual results to differ from HGS’s expectations in any forward-looking statement. Investors should consider this cautionary statement, as well as the risk factors identified in HGS’s periodic reports filed with the SEC, when evaluating HGS’s forward-looking statements.