A study by Tabata et al. 2020 has demonstrated that in human hepatoma cells, MAO-B plays a key role in converting geranylgeraniol (GGOH) to geranylgeranoic acid (GGA), and inhibiting or downregulating MAO-B activity using inhibitors or small interfering RNAs (siRNAs) reduced the intracellular level of GGA in these cells [37]. The gene discussed is MAOB; the disease is hepatocellular carcinoma.