Moreover, we show that tumor destruction is via local generation of cytotoxic peroxynitrites resulting from increased  ̇NO production (via upregulation of iNOS and recycling of citrulline generated by the breakdown of arginine from ADI-PEG20) and the localized production of superoxide anion radicals (O2•−) in the IR-targeted area (27) in addition to the enhanced phagocytosis by the macrophages/microglia. This evidence concerns the gene NOS2 and neoplasm.