NOS2 and neoplasm: M1 macrophages are induced by Th1 cytokines such as interferon γ (IFNγ) and tumor necrosis factor α (TNF-α) or by lipopolysaccharide (LPS) and typically attack microorganisms and tumor cells, and express inducible nitric oxide synthase (iNOS) and most of the TLRs [18].