ARG1 and neoplasm: Traditionally, they are dichotomized into M1 and M2 phenotypes: M1 macrophages, activated by IFN-γ, LPS, or TNF-α, exhibit tumoricidal and pro-inflammatory activity via secretion of IL-1β, IL-12, IL-23, and reactive nitrogen species; M2 macrophages, induced by IL-4, IL-10, or glucocorticoids, secrete IL-10 and TGF-β and express Arg1 and CD206, facilitating tissue repair, angiogenesis, and tumor progression (22).