Computational analysis in the protein–protein interaction network of HBV proteins has identified not only CDK4/ 6 but also CDK2 as HCC-related genes (Jiang et al. 2013), and interaction network of HCV proteins has identified CDKN2A (cyclin-dependent kinase inhibitor 2A) as one of the HCC related overlapped genes (Huang et al. 2012). The gene discussed is CDK4; the disease is hepatocellular carcinoma.