PTGS2 and colorectal cancer: Vitamin D insufficiency may therefore contribute to the persistence of chronic inflammation in the large intestine, which plays an important role in the development not only of colitis-associated but also of sporadic colorectal cancer [10,11]: Increased COX-2 activity enhances the risk of neoplastic transformation in ulcerative colitis by inducing pro-oncogenic mutations in colonic crypts that may give rise to dysplastic and cancerous lesions [12].