In the IL-23–induced psoriasis mouse model, gene expression of enzymes involved in PGE2 biosynthesis, including Ptgs2 encoding COX2, Ptges encoding membrane-associated PGE synthase (mPGES) 1, and Ptges2 encoding mPGES2, were all upregulated by IL-23 administration into the skin (see Fig E4, A, in this article's Online Repository at www.jacionline.org), which is consistent with the clinical observation that local PGE2 levels are increased in blister fluids from human psoriatic skin.58 Here, PTGES2 is linked to psoriasis.