SMAD1 and Hepatic fibrosis: Phosphorylated Smad1/5/8 competes with phosphorylated Smad2/3 to bind Smad4 to suppress the transcription of liver fibrosis-related genes, and BMP-7 promotes the phosphorylation of Smad1/5/8 in hepatic stellate cells (Chen et al., 2019b).