Fig. 6.

TGFβR1 mediates TGFβ-induced Smad1/5 phosphorylation in mPASMC. SB505124 (SB), an ALK4/5/7 inhibitor, prevented TGFβ-induced Smad1/5 phosphorylation, while dorsomorphin (DM), an ALK1/2/3/6 inhibitor, partly decreased TGFβ-induced Smad1/5 phosphorylation. Serum-starved cells were treated with 1 μM SB, 10 μM DM, or DMSO vehicle for 1 h before additional treatment with 2.5 ng/ml TGFβ1 or 20 ng/ml BMP4 for 1 h. Cell lysates were collected, and the protein expression level of the indicated Smads and GAPDH were detected using immunoblotting. Immunoblot images shown are representative of at least three independent experiments. For the densitometry analysis, n = 4 in each group; *P < 0.05.