Inhibition of the TGF-β receptor suppresses the expression of mesenchymal marker proteins in Dlg5-depleted cells.

<p><b>A:</b> LLc-PK1 cells were transfected with Dlg5 siRNA (KD) or control siRNA and stimulated with or without 4 ng/ml TGF-β. Two days after the addition of 2 µM ALK5 inhibitor II (TGF-β receptor inhibitor), cells were lysed and immunoblotted using the indicated antibodies. <b>B:</b> LLc-PK1 cells were transfected with a Smad7 expression plasmid or control plasmid and incubated for six hours. The cells were then treated with or without TGF-β (left panel) or transfected with Dlg5 siRNA or control siRNA (right panel). Two days after further incubation, cells were lysed and the expression of the indicated proteins was investigated by immunoblotting. Expression of β-tubulin was detected as a loading control. The results are representative of at least three independent experiments. Both pharmacological and physiological inhibition of TGF-β receptor suppressed the expression of SMA and fibronectin induced in Dlg5-depleted cells.