During tumor progression, oncogenic Ras supports pro-oxidant factors that induce activation of the response to DNA damage, dedifferentiation, genetic instability, hyper-proliferation, activation of subunits of the NADPH oxidase complex (NOX1/4), inactivation of antioxidants, ROS production from mitochondria or from cyclooxygenase-2 (COX2), resulting in additional mutations that stimulate tumor progression [87]. Here, PTGS2 is linked to neoplasm.