For example, increased expression of inducible nitric oxide (iNOS or NOS2, an enzyme expressed by M1 macrophages) together with elevated levels of Arg-1 (usually expressed by M2 macrophages) were observed in TAMs in Meth A – sarcoma, and prostate tumors, CT26 murine colon tumors [77]. This evidence concerns the gene NOS2 and colonic neoplasm.