(A-B) Smad2 and MRTFB synergistically enhanced TGF-β-induced VSMC marker gene promoter activity. pcDNA, Smad2, Smad3, or MRTFB cDNA was co-transfected individually or in combination with α-SMA (A) or SM22α promoter (B) as indicated followed by vehicle (Ctrl) or TGF-β treatment (5 ng/ml) for 16 hours. Luciferase assays were performed. Luciferase activity was normalized to renilla activity. *P<0.01 compared to Smad2 or MRTFB alone-transfected group with TGF-β treatment in A and B, respectively. (C-D) Smad2 and MRTFB synergistically enhanced TGF-β-induced mRNA expression of VSMC markers. Monc-1 cells were transfected with pcDNA, Smad2, Smad3, or MRTFB cDNA individually or in combination followed by vehicle (Ctrl) or TGF-β treatment (5 ng/ml) for 8 hours. α-SMA (C) and SM22α (D) mRNA expression was detected by qPCR and normalized to GAPDH expression. *P<0.01 compared to Smad2 or MRTFB alone-transfected group treated with TGF-β in both C and D, respectively.