In February 2007, we entered into an exclusive license, development and commercialization agreement with Schering-Plough for the development and worldwide commercialization of AN2690, including for the treatment of onychomycosis.

Pursuant to the agreement, Schering paid us a $40 million up-front fee and we have the right to require Schering to purchase up to $10 million of our capital stock. In addition to assuming sole responsibility for the costs of development and commercialization of AN2690, Schering has also agreed to pay us double-digit royalties up to twenty percent on sales of AN2690 and up to an additional $505 million if certain development, regulatory and commercial milestones for onychomycosis are achieved. Schering is also obligated to pay us additional fees for each additional indication for which Schering develops AN2690 treatments if certain milestones are achieved. We retained the option to co-promote AN2690 for the treatment of onychomycosis to dermatologists in the United States, subject to certain conditions. Schering did not acquire any rights to any of our other product candidates under this agreement.

In October 2007, we entered into a research and development collaboration, option and license agreement with GSK for the discovery, development, manufacture and worldwide commercialization of boron-based systemic therapeutics for at least eight product options in up to four target-based projects, one of which will target the Hepatitis C Virus (HCV) and others of which will be in the area of antibiotics. Under the agreement, we will collaborate with GSK to identify and develop boron-based small molecule product candidates.

Pursuant to the agreement, GSK paid us a $12 million non-refundable, non-creditable up-front fee in October 2007 and we have the right to require GSK to purchase $10 million of our capital stock in a private placement. In each project, GSK has the option to obtain an exclusive license to develop, commercialize and market worldwide a specified number of product candidates once they have achieved proof of concept criteria. In the HCV project, GSK also has an option to obtain such an exclusive license at the time a product candidate is selected. We will be primarily responsible for the discovery and development of each product candidate from the research stage until GSK exercises an option for such product candidate, at which point GSK will assume sole responsibility for the further development and commercialization of such product candidate on a worldwide basis. GSK is obligated to make payments to us if certain development, regulatory and commercial milestones are met on a compound-by-compound basis. Total potential payments for discovery, development, regulatory and commercial milestones range up to $252 million to $331 million per product candidate. GSK is further obligated to pay us tiered double-digit royalties, with the potential to reach the mid-teens, on annual net sales of products containing optioned compounds in jurisdictions where there is a valid patent claim covering the product and lesser royalties for sales in jurisdictions where there is no valid patent claim. In the event that GSK exercises its option for a product candidate in the HCV project at the candidate selection stage, the discovery, development and regulatory milestone payments for which we are eligible and the product royalties payable to us would be lower.