TGFB1 and cancer: MDSC has potent immunosuppressive activity through multiple pathways: promoting Tregs’ production and promoting fibroblast differentiation into cancer-associated fibroblasts (CAF) depleting L-arginine eliminates key trophic factors required for T cell proliferation, nitrates chemokines and blocks CD8+ T cells from entering the tumor, and produces immunosuppressive cytokines such as IL-10 and TGF-β (61, 62).