TGFB1 and neoplasm: The activated TAMs and MDSCs secrete tumor growth factor-β (TGF-β), among other cytokines, which negatively regulates the anti-tumor immune response using various mechanisms, such as conversion of naïve CD4+ T cells into Tregs; activation of Tregs; and inhibition of effector T-cell differentiation, maturation, and activation [36,38].