One network contains six pathways, i.e., glucagon signaling pathway, thermogenesis, Parkinson’s disease, oxidative phosphorylation, non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma; the oxidative phosphorylation pathway had the largest degree in this pathway network (Figure 6 left), which was critical for energy metabolism. The gene discussed is GCG; the disease is hepatocellular carcinoma.