Knockdown of Smad2 suppresses HRG-β1-induced expressions of Snail and fibronectin in SK-BR-3 (a) and MCF7 (b) cells. (a, b) The cells were transfected with control or Smad2 siRNAs prior to treatment with 25 ng/ml of HRG-β1. After incubation for a further 24 h, the expressions of phospho-Smad2, Smad2, Snail, and fibronectin were analyzed by western blotting. β-actin was reprobed as a loading control. Data represent the means ± SD of three independent experiments. *P < 0.05, **P < 0.01, significant difference.