PAK2 and Hepatic fibrosis: HUC-MSCs were transplanted into mice with carbon tetrachloride- (CCl4-) induced liver fibrosis, the result showed that HUC-MSC transplantation significantly ameliorated the severity of CCl4-induced liver fibrosis, attenuated collagen deposition, improved liver function by reducing the expression of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum, upregulated miR-455-3p, and suppressed PAK2 expression of liver tissue in mice.