However, our results showed that lack of mPGES-1 conversely exacerbates colitis and suppresses PGE2 production, even though levels of anti-colitis PGD2 increase; these findings suggest that during colitis, mPGES-1–driven PGE2 plays a greater role than PGD2 as an anti-colitis prostanoid. Here, PTGES is linked to colitis.