TGFB1 and breast carcinoma: Although TGF-β1 has the potential to activate multiple signaling pathways, our data in this study showed that TGF-β1 alone was inefficient in inducing the sustained activation of Smad and non-Smad pathways in non-invasive breast cancer cells, which could explain the inefficiency of TGF-β1 in inducing EMT of non-invasive tumor cells in vitro reported previously [7].