TGFB1 and breast cancer: Small chemical molecules are developed to block TGF-β signaling by inhibiting the phosphorylation function of TGFBRs, among them SB431542 is widely used to inhibit TGFBR-I in breast cancer therapy [86,87] and LY2109761 is another TGFBRs inhibitor that is applied in treating pancreatic cancer [88].