ATG5 and liver cancer: In addition to ATG5 and ATG17, autophagic protein Beclin 1 deficient mice model has a high incidence of hepatocellular carcinoma.46 Endocrines such as thyroid hormone suppresses hepatocarcinogenesis in diethylnitrosamine (DEN) induced mice model, indicating autophagy may be a gatekeeper in carcinogen-induced liver cancer.47 In other chemical carcinogen-induced tumorigenesis, autophagy plays a protective mechanism that inhibits DMBA/TPA-induced skin cancer.34 All the evidences indicate that autophagy-related genes could be a promising suppressor of spontaneous and induced tumorigenesis.