In summary, these data expand the role for SOX9 in regulating components of the ECM and begin to provide insight into its regulation by signaling pathways linked to fibrosis and related pathologies in the liver and other sites, such as the skin, kidney, lung, and major blood vessels.18 Finally, given the potential use of serum OPN as a biomarker for the severity of liver damage in patients with HBV or HCV,11, 12 it is possible that additional downstream ECM targets of SOX9 action may be useful in helping to stage and predict the severity of liver fibrosis. This evidence concerns the gene SPP1 and Hepatic fibrosis.