In mammary carcinoma, TGF-β appears to play a key role in maintaining the mammary epithelial (cancer) stem cell pool, in part by inducing a mesenchymal phenotype, while differentiated, estrogen receptor-positive, luminal cells are unresponsive to TGF-β because the TGFBR2 receptor gene is transcriptionally silent [59]. This evidence concerns the gene TGFB1 and breast carcinoma.