CSF2 and neoplasm: Tumor-derived GM-CSF, IL-6, IL-1β, TGF-β, IL-13, IFN-γ, CXCL5 have also been found to regulate MDSC accumulation and the polarization of tumor-infiltrating granulocytic MDSC (G-MDSC) toward an immunosuppressive phenotype (30, 31).