Microsomal prostaglandin E2 synthase-1 (mPGES1) is a molecule belonging to the MAPEG superfamily and is involved in the conversion of PGH2 to excess PGE2 associated with pain and inflammation. Gesynta Pharma AB presented first data on the mPGES1 inhibitor GS-248 for the treatment of pain and inflammation. In their experiments, GS-248 demonstrated a human whole-blood assay (hWBA) IC50 of 0.4 nM, and hWBA activity about 1000-fold more potent than that of celecoxib. No cross reactivity was observed with COX1 or COX2. Moreover, the compound showed IC50 values for human, dog, rat/mouse and minipig mPGES1 of 2.5, 1.3, > 1000 and 23 nM, respectively.