TGFB1 and breast cancer: These data suggest that FAK selectively regulates the initial steps of tumor cell dissemination stimulated by TGF-β, a result that is consistent with our findings of the requirement of FAK in (a) mediating EMT stimulated by TGF-β (Figure 5) and (b) preventing primary colonization of breast cancer cells in the lung (Figure 6b, weeks 2 to 3), but not their secondary outgrowth (Figure 6b, weeks 3 to 4).