Fig. 2.

Shear stress induces sustained phosphorylation of Smad1/5 in MG63 cells through BMPRIA. (A) MG63 cells were kept as controls or subjected to shear stress (12 dynes/cm²) for 10 min, 30 min, 1 h, 3 h, 6 h, and 24 h, and their Smad 1/5 phosphorylation was determined by Western blot analysis. (B) MG63 cells were exposed to shear stress of 2, 12, and 20 dynes/cm² for 30 min. (C) MG63 cells were kept as controls (−) or pretreated with Noggin (100 ng/ml) for 1 h (+N) and then subjected to flow or BMP-4 (100 ng/ml) for 30 min. (D) MG63 cells were transfected with siRNAs at various concentrations (5, 15, 30, and 40 nM), and their BMPRIA and BMPRIB protein expressions were examined by Western blot analysis. (E) MG63 cells were transfected with control siRNA (siCL) or specific siRNA of BMPRIA (siRIA) or BMPRIB (siRIB) (40 nM each) for 48 h and then kept as controls (C) or exposed to flow (S) for 30 min. Data in A and B are means ± SEM from three independent experiments and presented as percentage changes in band density from control cells normalized to Smad1/5 protein levels. The results in C–E are representative of triplicate experiments with similar results. *, P < 0.05 vs. static control cells.