NPAS2 and hepatocellular carcinoma: To determine the role of the positive limb of the core circadian genes in HCC, we first analyzed the mRNA expression level of the mammalian clock machinery genes (NPAS2, BMAL1 and CLOCK) from four public data set from HCC patients and found that NPAS2 exhibited a significant upregulation in tumor tissues when compared with paired adjacent nontumor tissues (Supplementary Figure S1A).