TGFB1 and renal fibrosis: In addition, overexpression of latent TGFβ1 was shown to decrease both SMAD2/3 activation (transcription factors of canonical TGFβ1 signaling) and the number of myofibroblasts (60), which is in line with findings that SMAD3 knockout mice are protected from renal fibrosis (61, 62).