On the other hand, a group of cytochrome P450 enzymes localized to the hepatic microsomal fraction are known to be able to oxidize isoprenols such as geraniol, farnesol, GGOH, and retinol [15,16,17]; however, whether cytochrome P450 enzymes are involved in the oxidation of GGOH in MAOB knockout hepatoma cells has not been investigated. The gene discussed is MAOB; the disease is hepatocellular carcinoma.