It is uncertain why PUFAs are depleted in HCC, especially since long chain acyl CoA synthetase 4, which activates arachidonic acid for phospholipid biosynthesis or oxidation, and fatty acid desaturase 2, which participates in long chain PUFA synthesis, have both been shown to be enhanced in HCCs. This evidence concerns the gene FADS2 and hepatocellular carcinoma.