Yi et al. have reported that high level of NPAS2 mRNA expression is associated with increased disease free and OSs in breast cancer.11 In contrast, our data have demonstrated that NPAS2 is frequently upregulated in HCC cell lines and tissues and high expression of NPAS2 is associated with the aggressive clinical characteristics and poor prognosis in HCC patients. The gene discussed is NPAS2; the disease is hepatocellular carcinoma.