MDC1 and malignant colon neoplasm: In RKO colon cancer cells, after DNA damage induction by ionizing radiation, ATM serine/threonine kinase (ATM) phosphorylated threonine 392 of KAT8, which recruited the mediator of DNA damage checkpoint protein 1 (MDC1) and BRCA1 DNA repair associated (BRCA1) to DNA damage sites for repair, thereby promoting colon cancer cell proliferation [66,67].