Using an in vitro HCV infection system, HCV core protein (genotype 1b) decreased PER2 and CRY2 protein levels in infected HuH-7 cells (human hepatoma cell line), whereas overexpression of Per2 in HuH-7 cells reciprocally decreased HCV RNA replication (Benegiamo et al., 2012). The gene discussed is PER2; the disease is hepatocellular carcinoma.