XRCC6 and neoplasm: The conclusion of KU70-K570 methylation was based on in vitro observation of KU70 methylation by SETD4, a reduction of KU70 methylation upon SETD4 downregulation in tumor cells with high levels of SETD4 and an induction of KU70 methylation due to exogenous expression of SETD4 in cells with modest endogenous SETD4 (24).