Combining these with the current findings that the ATM and ATR residue mutated in cancer are tissue specific (Fig. 2b, c and Supplementary Fig. 2a), and that some regions of the respective enzyme complexes are enriched for residues that are mutated in a specific cancer type (Fig. 3c–e, Fig. 4d and Supplementary Fig. 4a) suggest the cancer relevance of separation of function ATM/ATR mutations leading to the loss of a tissue-specific function(s). Here, ATR is linked to cancer.