Expression of COX-1 and -2 as well as 5-lipoxygenase enables TCs to synthesize prostaglandin D2 (PGD2) and -E2 (PGE2) and cysteinyl leukotriene C4 (LTC4) (55), with important physiological roles both during homeostasis (e.g., GI motility, secretion, and mucosal protection) as well as under pathological conditions (e.g., inflammatory bowel disease (IBD), and colorectal cancer) (83, 84). Here, PTGS1 is linked to inflammatory bowel disease.