TGFB1 and breast cancer: In breast cancer, EMT is largely regulated by the transforming growth factor beta (TGF-β)/mothers against decapentaplegic homolog (Smad) signaling pathway, in which phosphorylated Smad2 and Smad3 form a complex with Smad4 and translocate into the nucleus to regulate EMT-related genes such as N-cadherin and Vimentin [6,7,8,9].