HAS2 and Hepatic fibrosis: HSCs are responsible for HAS2 expression and HA synthesis in liver fibrosis.4 Quiescent HSCs do not express HAS2 or produce HA.4 Upon HSC activation, HAS2 expression and HA production are dramatically upregulated.4 Like ECM-producing lung fibroblasts, TGF-β is a potent inducer of HSC transdifferentiation to myofibroblasts and HAS2 overexpression.