Moreover, a study indicated that the expression levels of WW-domain-containing oxidoreductase (WWOX) and hypoxia-inducible factor-1 (HIF-1) may impact the susceptibility of HCC cells to ADI-PEG 20, implying the potential use of these proteins as biomarkers for ADI-PEG 20 in liver cancer treatment [28]. This evidence concerns the gene WWOX and hepatocellular carcinoma.