SMAD3 and kidney disorder: BMP-7 is a natural antagonist for TGF-β through inhibiting the TGF-β/Smad3, which has been demonstrated on various renal disease models (Hruska et al., 2000; Zeisberg et al., 2003; Wang et al., 2006a; Sugimoto et al., 2007; Luo et al., 2010; Meng et al., 2013).