Ward et al. [26] observed downregulation of epithelial marker (E-cadherin) expression that was accompanied by the upregulation of mesenchymal markers (TGFB2, SMAD3 and ZYX) and EMT transcription factor, SNAI2, in tamoxifen-resistant breast cancer cells compared with the parental cells. This evidence concerns the gene SMAD3 and breast cancer.