NOS2 and neoplasm: NOS-derived NO is highly pleiotropic in terms of biological action, playing a role in many different physiological and pathophysiological processes, ranging from vasodilation (eNOS), neurotransmission (nNOS), and antimicrobial activity (iNOS) on the one hand, to chronic inflammation, tumor initiation, and tumor progression on the other, the last three typically associated with iNOS [4,5,6,7].