NOX4 and hepatocellular carcinoma: Indeed, NOX4 is upregulated by TGF-β through a Smad-dependent mechanism, but transactivation of the EGFR by TGF-β impairs its effects on NOX4 expression in a PI3K-dependent mechanism.20 For this reason, we evaluated the role of CAV1 on TGF-β-induced EGFR activation in HCC cells.