SMAD7 and Hepatic fibrosis: It has been demonstrated that Dnmt1 catalyzes DNA methylation and subsequently leads to the transcriptional repression of genes associated with fibrogenesis; for example, the induction of RASAL1 hypermethylation contributes to renal fibroblast activation (17), the mediation of PTEN hypermethylation (33) and the epigenetic repression of Smad7 (34) in liver fibrosis.