Mechanistically, CRL4B complex coordinates with PRC2 complex to repress miR34a expression thus upregulates miR34a target genes including MYCN. CUL4B upregulation is associated with miR34a downregulation and upregulation of miR34a targets in CRC tissues and poor survival rates, suggesting that elevated CUL4B expression can serve as predictive markers for patients with CRC. Here, MYCN is linked to colorectal carcinoma.