An additional study has demonstrated that higher NOX4 mRNA expression levels in HCC patients are significantly associated with prolonged overall survival, whereas increased NOX1/NOX2 expression is significantly correlated with a poor overall survival, therefore indicating that while NOX4 behaves as a tumor suppressor in HCC, NOX1 and NOX2 may act as tumor promoters [155]. Here, NOX4 is linked to hepatocellular carcinoma.