Terminal enzyme of the cyclooxygenase (COX)-2-mediated prostaglandin E2 (PGE2) biosynthetic pathway. Catalyzes the glutathione-dependent oxidoreduction of prostaglandin endoperoxide H2 (PGH2) to prostaglandin E2 (PGE2) in response to inflammatory stimuli (PubMed:18682561, PubMed:10377395, PubMed:12672824, PubMed:12460774, PubMed:10869354, PubMed:12244105). Plays a key role in inflammation response, fever and pain (By similarity). Catalyzes also the oxidoreduction of endocannabinoids into prostaglandin glycerol esters and PGG2 into 15-hydroperoxy-PGE2 (PubMed:12244105, PubMed:12672824). In addition, displays low glutathione transferase and glutathione-dependent peroxidase activities, toward 1-chloro-2,4-dinitrobenzene and 5-hydroperoxyicosatetraenoic acid (5-HPETE), respectively (PubMed:12672824). prostaglandin H2 = prostaglandin E2 2-glyceryl-prostaglandin H2 = 2-glyceryl-prostaglandin E2 prostaglandin G2 = (15S)-15-hydroperoxy-prostaglandin E2 1-chloro-2,4-dinitrobenzene + glutathione = 2,4-dinitrophenyl-S-glutathione + chloride + H(+) (5S)-hydroperoxy-(6E,8Z,11Z,14Z)-eicosatetraenoate + 2 glutathione = (5S)-hydroxy-(6E,8Z,11Z,14Z)-eicosatetraenoate + glutathione disulfide + H2O Induced by interleukin IL1B. kcat is 50 sec(-1) for prostaglandin H2 as substrate (PubMed:12672824). kcat is 75 sec(-1) for prostaglandin H2 as substrate (PubMed:12672824). kcat is 21 sec(-1) for glutathione as substrate (PubMed:12672824). Lipid metabolism; prostaglandin biosynthesis. Homotrimer. Colocalizes with PTGS1/COX-1 and PTGS2/COX-2 in the perinuclear compartment. Induced by the interleukin IL1B (PubMed:10377395, PubMed:10760517). Induced By p53/TP53 (PubMed:9305847). Belongs to the MAPEG family.