EP 4 is a G s protein-coupled receptor that, by elevating the second messenger cAMP, plays important roles in bone formation and resorption, cancer, and atherosclerosis. 1,2,3 CJ-023423 is a potent and selective antagonist of the EP 4 receptor (K i = 13 and 20 nM for human and rat EP 4, respectively). 4,5 It inhibits PGE 2-evoked elevation in ...