Thus, we analyzed the specific process of the chemical carcinogenesis pathway (Figure S12) and found that MAOA could participate in the pathogenesis and progression of HCC and other cancers through multiple genes, namely CYP1A1, CYP1A2, CYP2A, CYP2E1, CYP3A4, GST, HSD11B1, NAT, NAT2, and UGT. The gene discussed is CYP3A4; the disease is cancer.