Genetically engineered mice lacking iNOS (iNOS−/- mice) or mice treated with iNOS inhibitors have reduced colon and gastric tumour formation, associated with decreased levels of pro-inflammatory cytokines produced by innate immune cells, such as TNF-α and IL-6, and diminished nitrosative and oxidative stress [[14], [15], [16]]. This evidence concerns the gene NOS2 and gastric neoplasm.