PER1 and colonic neoplasm: For instance, a recent study in HEK-293 and colon cancer cells showed that overexpressed MYC bound the PER1 promoter exclusively, and rather than transactivating expression, this binding led to a downregulation of PER1 due to competitive inhibition of CLOCK-BMAL1 promoter occupancy, which would presumably also lead to circadian disruption (Repouskou and Prombona, 2016).