TGFB1 and neoplasm: An experiment conducted by Stromnes et al. [39] showed that depletion of granulocytic MDSC (GR MDSC) in PDA models in vivo and in vitro could increase the internal accumulation of activated CD8+ T cells and apoptosis of tumor epithelial cells.In addition, MDSCs can induce Treg proliferation by secreting IL-2 and TGF-β to mediate immunosuppression indirectly [40].