To further determine whether NPAS2 and BMAL1 co-binds to the CDC25A promoter, we performed ChIP-PCR assay in HCC cells and observed that BMAL1 directly binds to the promoter of CDC25A (Figure 8b and Supplementary Figure S4D), suggesting an essential role of BMAL1 in NPAS2-mediated transactivation of CDC25A. Here, NPAS2 is linked to hepatocellular carcinoma.