A number of ALK5 inhibitors such as EW-7195, EW-7203 and IN-1130 have shown to effectively block TGF-β1-induced SMAD signaling, EMT and breast cancer metastasis in vivo [181,182,183], demonstrating the potential of these small molecules to prevent breast cancer metastasis to the lung. This evidence concerns the gene TGFB1 and breast cancer.