Overexpression of HO-1 induces the expression of Cyclin Dependent Kinase 4 (CDK4) and promotes the occurrence of liver cancer; however, a feedback loop may exist between IL-6 and HO-1, thus HO-1 can be induced as an antitumor gene through the IL-6/JAK/STAT3 pathways 59, 60. This evidence concerns the gene CDK4 and liver cancer.