MAOB and hepatocellular carcinoma: In 94-week-old mice, Maob mRNA expression level was further and significantly reduced in hepatoma tissue compared to that of its surrounding normal liver tissue, which was 40% of the hepatic Maob mRNA level of 6-week-old mice (Figure 4A), whereas there was no significant difference in Maoa mRNA expression level between hepatoma tissue and the normal liver tissue of 94-week-old mice (Figure 4B).