In breast cancer, TGF-β can either promote or inhibit tumor-initiating cells (breast TICs, or BTICs), which are responsible for cancer initiation, propagation, and metastasis (Bierie and Moses, 2009, Bruna et al., 2012, Mani et al., 2008, Scheel et al., 2011). This evidence concerns the gene TGFB1 and breast cancer.