SMAD2 and Hepatic fibrosis: Subsequently, phosphorylated Smad2/3 and Smad4 form a complex and then translocate into the nucleus to regulate the transcription of downstream pro-fibrosis genes, leading to liver fibrosis (Greenwel et al., 1997; Ghosh et al., 2000; Hata and Chen, 2016; Yoshida et al., 2018).