Furthermore, based on SOX9′s additional roles in regulating both COL117 and collagen type 4 (COL4),23 there is the potential that SOX9 could be important in chronic cholestatic liver injury by regulating all these ECM components as part of the pathology of primary biliary cirrhosis (PBC) and primary sclerosing cholangitis. This evidence concerns the gene SOX9 and primary biliary cholangitis.