TGFB1 and neoplasm: Thus, MSC–derived exosomes, which contain TGF-β, C1q, and semaphorins can also induce the differentiation of MDSCs into M2-polarized macrophage at tumor beds by driving Programmed Death-ligand 1 (PD-L1) overexpression and by inducing differentiation of macrophage with enhanced L-Arginase activity and IL-10 secretion (135).