PTGS2 and malignant colon neoplasm: It is reported that greater than 80% of colon cancers in humans have increased COX-2 levels when compared to adjacent normal tissue (Williams et al, 1997), and overexpression of COX-2 has been identified as an early central event in colon carcinogenesis (Kargman et al, 1995; Tsuji and Dubois, 1995; Boolbol et al, 1996; Reddy et al, 1996; Tsuji et al, 1997).