Clock genes: Their role in colorectal cancer

Figure 1 The molecular mechanism of the cellular circadian system. CLOCK1/BMAL1 and NPAS2/BMAL1 complexes promote the expression of PER and CRY. PER is phosphorylated by CK1ε kinase resulting to its degradation while the accumulation of CRY leads to the formation of PER/CRY/CK1ε complex which inserts to the nucleus and down-regulates the CLOCK1 and BMAL1 activity. Among the transcriptional targets of CLOCK1 and BMAL1 are some cell cycle mediators, tumor suppressor genes and oncogenes regulating cell cycle, cellular metabolism and DNA repair.