Inducible nitric oxide synthetases (iNOS) are also probably involved in the carcinogenesis of colorectal cancer because activation of iNOS by LPS is associated with activation of COX-2 signaling, and inhibition of iNOS by iNOS inhibitor 1400W or iNOS siRNA may nullify production of nitric oxide (NO) and PGE226. Here, PTGS2 is linked to colorectal cancer.