NOS2 and neoplasm: According to the activation mechanism, macrophages are classified as M1 (activated by IFN-γ and TLR ligands, the expression of higher levels of IL-12, IL-23, MHC II, and inducible nitric oxide synthase, and tumoricidal) or M2 (activated by IL-4 and IL-13, the expression of higher levels of IL-10 and TGFβ, and facilitate tumor progression) [73, 74].