(B) Upper panel: Immunoblots of SM-calponin, phosphorylated Smad2 (p-Smad2), and TGFR1 expression in control and FRS2 knockdown HASMCs transduced with or without let-7b lentiviruses. Blots are representative of three independent experiments. Bottom panels: Band intensities of SM-calponin and p-Smad2 were normalized to GAPDH or Smad2 and expressed as a fraction of a control value. 