TGFB1 and breast cancer: Thus, in order to analyze the role of TGF-β1 as a common regulator of the MMPs and their inhibitors in a breast cancer cell model, we treated the highly invasive MDA-MB-231 cell line with different concentrations (0, 1, 5 or 10 ng/mL) of recombinant TGF-β1 for 20 h.