MLYCD and hepatocellular carcinoma: Human MLYCD encodes Malonyl-CoA decarboxylase that catalyzes the conversion of malonyl-CoA into acetyl-CoA and carbon dioxide and has been proven by the previous study to promote FAO in cancer cells.29 We, therefore, hypothesize that MLYCD may be the downstream factor involving in PIWIL1-mediated FAO-associated HCC proliferation.