PTGS2 and ulcerative colitis: Meanwhile, the importance of the IL-17/IL-23 axis is well documented for the pathogenesis of Crohn's disease and ulcerative colitis in humans (Clevers, 2006), and Cox2-derived lipids, including prostaglandin E2, are potent inflammatory mediators that promote tumor growth and metastasis (Wang et al., 2005; Xia et al., 2012).