(E) Control and FRS2 knockdown HASMCs were cultured in the growth medium (M231 + SMGS) at day 0 then switched from growth conditions to differentiation medium (M231 + SMDS) for 6 days with or without let-7b lentiviruses. Immunoblots of smooth muscle markers, phosphorylated Smad2 (p-Smad2), and TGFR1 expression in control and FRS2 knockdown HASMCs with or without let-7b lentiviruses. Blots are representative of three independent experiments. 