When similar experiments were performed on isogenic AtmC/C and corresponding Atm-/- leukemia, irinotecan has no significant benefit in either groups (Figure 4—figure supplement 1C–F, p≥0.05 in all pairs), suggesting loss of ATM-mediated DNA damage responses alone is not sufficient to explain the hypersensitivity of AtmKD/- leukemia to Topo1 inhibitors. This evidence concerns the gene ATM and leukemia.