PRESS RELEASE

Galapagos Enters Strategic Alliance In Inflammatory Diseases With Merck & Co., Inc.

Galapagos to Discover Small Molecule Candidate Drugs for
Preclinical Development

Upfront Fee, Milestones on Preclinical and Clinical Development of Small Molecule Candidates, Plus Royalties on Worldwide Sales

MECHELEN, BELGIUM, April 20, 2009 - Galapagos NV (Euronext: GLPG) announced today that it has entered into a multi-year global strategic alliance with Merck & Co., Inc., through an affiliate, to develop potential new therapies in inflammatory diseases.

Galapagos will be responsible for the discovery and pre-clinical development of new small molecule candidate drugs based on novel Galapagos targets. Merck will have the exclusive option to license each candidate for clinical development and commercialization on a worldwide basis. The alliance will make use of Galapagos’ proprietary SilenceSelect® target discovery platform for identification of novel targets in inflammatory diseases. After validation, targets will be selected by a joint steering committee and entered into screening and chemistry by Galapagos. Merck has the option to acquire an exclusive license to each candidate drug and upon exercise of such an option. Merck will be responsible for the development and commercialization of the candidate drug. Galapagos may execute phase I clinical studies and will have the right to further develop and commercialize certain compounds for which Merck does not exercise its exclusive option.

Under the terms of the agreement, Galapagos will receive an upfront fee of EUR 2.5 million from Merck. In addition, Galapagos is eligible to receive discovery, development and regulatory milestone payments that could potentially exceed EUR 192 million total for multiple products, as well as specific sales milestones and royalties upon commercialization of any products covered under the agreement.

“This new alliance with Merck in inflammatory diseases, our sixth pharma alliance to date, underscores the quality and versatility of Galapagos’ target discovery platform,” said Onno van de Stolpe, CEO. “Galapagos has proven it delivers on its alliance programs, making us attractive to potential pharma partners seeking to fill their pipelines with medicines based on novel modes of action.”

About Galapagos

Galapagos (Euronext: GLPG; OTC: GLPYY) is a drug discovery and development company with small molecule programs in bone and joint diseases, bone metastasis, cachexia, anti-infectives and metabolic diseases. It has established risk sharing alliances with GSK, Janssen Pharmaceutica, Eli Lilly and Merck. Through an alliance with MorphoSys, Galapagos is also developing new antibody therapies in bone and joint diseases. Its division BioFocus DPI offers a full suite of target-to-drug discovery products and services to pharmaceutical and biotech companies and to patient foundations, encompassing target discovery and validation, screening and drug discovery through to delivery of pre-clinical candidates. Galapagos currently employs 480 people and operates facilities in six countries, with global headquarters in Mechelen, Belgium. More info at: www.glpg.com. CONTACT Galapagos NV

Forward-Looking Statement for Merck & Co., Inc.

This news release contains “forward-looking statements” as that term is defined in the Private Securities Litigation Reform Act of 1995. These statements are based on management's current expectations and involve risks and uncertainties, which may cause results to differ materially from those set forth in the statements. The forward-looking statements may include statements regarding product development, product potential, or financial performance. No forward-looking statement can be guaranteed and actual results may differ materially from those projected. Merck undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events, or otherwise. Forward-looking statements in this booklet should be evaluated together with the many uncertainties that affect Merck's business, particularly those mentioned in the risk factors and cautionary statements in Item 1A of Merck's Form 10-K for the year ended Dec. 31, 2008, and in any risk factors or cautionary statements contained in the Company's periodic reports on Form 10-Q or current reports on Form 8-K, which the Company incorporates by reference.

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