As noted above, studies in cancer cells have shown that the Rev7–Shieldin effector complex facilitates NHEJ by blocking 5′ end resection and HR (Xu et al., 2015; Boersma et al., 2015; Mirman et al., 2018; Findlay et al., 2018; Gupta et al., 2018; Ghezraoui et al., 2018; Cejka and Symington, 2021). This evidence concerns the gene MAD2L2 and cancer.