Epigenetic modifications are responsible for gene downregulation, such as DNA methylation, histone deacetylation and histone methylation, especially the histone H3 lysine 27 trimethylation (H3K27me3) regulated by EZH2 and histone H3 lysine 9 dimethylation regulated by the G9a, which play important roles in HSCs activation and liver fibrosis.31, 32, 33, 34. The gene discussed is EHMT2; the disease is Hepatic fibrosis.