ARG1 and neoplasm: In contrast, M2 macrophages, characterized by the expression of arginase 1 (Arg-1) and anti-inflammatory cytokines, such as IL-10, commonly have a low level of iNOS5–7 and can assist tumor development by inducing angiogenesis, remodeling the extracellular matrix, stimulating cancer cell proliferation, and inhibiting adaptive immunity.