SMAD4 and breast carcinoma: Moreover, the overexpression of FOXM1 in breast cancer can interact with Smad3/Smad4 and inhibit the binding of TIF1γ to Smad4 to prevent its ubiquitination, which can attenuate the inhibitory effects of TIF1γ on TGF-β signaling to promote the metastasis of breast cancer (26).