In our research, ACE2 and the three ACE2-related genes – NR3C2, MME, and MEP1B – in the PPI subnetwork clustered simultaneously in the metallopeptidase activity function, which suggests that metallopeptidase activity may be one of the mechanisms by which ACE2 plays a role in HCC. The gene discussed is MEP1B; the disease is hepatocellular carcinoma.