TGFB1 and cancer: Notably, within the tumor microenvironment, TGF-β plays crucial roles with regard to tumor immunity, and targeted TGF-β signaling blockade in helper T cells elicits an effective tissue-level cancer defense response that can provide a basis for therapies that are directed toward the cancer microenvironment (20); TGF-β is also the most potent immunosuppressor against cancer cells, and this significant effect is mediated in multiple ways, including polarization of macrophages to M2 cells.