In addition, TGF-β and C1q contained in BC-MSCs-EVs induce upregulation of PD-L1 in MDSCs and M2 macrophages along with downregulation of PD-1 in infiltrating T cells, which maintains the immunosuppressive TME, thus overcoming the T cells-mediated anti-tumor immune response [122]. Here, TGFB1 is linked to neoplasm.