As SUMOylation, a process in which SUMO proteins are covalently attached to a specific lysine of BMAL1, has been shown to control the circadian clock, and the deregulated methylation status of circadian clock genes has also been demonstrated in various types of cancers, the mechanisms of transcriptional and epigenetic regulation are considered critical for a better understanding of the circadian clock regulation and deregulation during leukemogenesis [106,107]. Here, CLOCK is linked to cancer.