ATM and neoplasm: We propose that the best explanation for these results is that most distal NHEJ at interstitial DSBs in the EJ-30 tumor cell line occurs through A-NHEJ, which is inhibited by Mirin, while most distal NHEJ at subtelomeric DSBs occurs through C-NHEJ, which is not affected by Mirin, but is ATM dependent (Figure 6).