Microsomal prostaglandin E (PGE) synthase-1 (mPGES-1; EC 5.3.99.3) is a member of the MAPEG (membrane-associated proteins involved in eicosanoid and glutathione metabolism) superfamily, showing significant homology with other MAPEG superfamily proteins, including microsomal glutathione-S-transferase (GST)-1-like 1 (MGST-1), 5-lipoxygenase (LOX)-activating protein (FLAP) and leukotriene C4 synthase (LTC4). It is a glutathione dependent inducible enzyme that couples with cyclooxygenase-2 (COX-2) for the biosynthesis of Prostaglandin E2 (PGE2); a bioactive lipid that can elicit a wide range of biological effects associated with inflammation and cancer.