EPIX Pharmaceuticals, Inc. has earned a $3 million milestone payment under its collaboration with GlaxoSmithKline related to the first of three discovery stage programs. EPIX has identified three lead candidates that will move forward into lead optimization in this first G-protein coupled receptor (GPCR) discovery program.     The two companies entered the multi-target collaboration in December 2006 to discover, develop and market medicines targeting four G-protein coupled receptors (GPCRs) ...