Figure 2.

TGF-β1/SMAD signaling pathways in hepatic fibrosis. In hepatic fibrosis, TGF-β1 triggers SMAD2/3, whereas BMP7 activates SMAD1/5/8. Then the phosphorylated SMAD2/3 or SMAD1/5/8 form complexes with SMAD4 and shuttle into the nucleus to regulate gene transcription by binding to DNA sequences or cofactors. In addition, TGF-β1 also activates the inhibitory SMADs (SMAD7) to negatively regulate their signals. Abbreviations: BMPRI, bone morphogenetic protein receptor type I; p, phosphorylation.