CHEK1 and esophageal squamous cell carcinoma: Preclinical data have also demonstrated that 53BP1 can regulate cell cycle arrest through the modulation of TP53, CHK1, and CHK2 gene expression in ESCC; specifically, targeted downregulation of the 53BP1 protein has been shown to cause a reduction in p53 gene expression, but to be negatively correlated with CHK1 and CHK2 gene expression [133].