PTGS2 and inflammatory bowel disease: COX-2 is induced in colonic epithelium in active inflammatory bowel disease (IBD) [17] and its up-regulation results in elevated levels of prostaglandin (PG), in particular PGE2 that is a downstream mediator of COX-2 and promotes many carcinogenic pathways including cellular proliferation, inhibition of apoptosis and angiogenesis [18].