ARG1 and neoplasm: More specifically, MDSCs are known to produce Arg-1, iNOS, IL-10, TGF-β, and COX-2 to inhibit the proliferation and function of T cells.348 In addition to their immune suppressive function, MDSCs were shown to promote tumor progression by remodeling of the TME and facilitated tumor angiogenesis by producing cytokines, such as VEGF and FGF.349 In addition, MDSCs were observed to participate in the formation of premetastatic lesions, and metastasis by infiltrating primary tumors.