(C) Left: Immunoblot analysis of TGFRs, phosphorylated Smad2 (p-Smad2), and phosphorylated Smad3 (p-Smad3) in control and FRS2 knockdown HASMCs. Blots are representative of four independent experiments. Right: Band intensities of p-Smad2, p-Smad3, TGFR1, and TGFR2 were normalized to Smad2/3 or GAPDH and expressed as a fraction of a control value. Results are expressed as means ± SD (*p<0.05; ***p<0.001 compared to control; unpaired two-tailed Student's t test). 