PRKDC and chronic myelogenous leukemia, BCR-ABL1 positive: Similarly, concomitant NU5455 (5 μM) treatment did not alter the response of human chronic myeloid leukemia HAP-1 DNA-PK–null cells to IR, but markedly increased the clonogenic cell-killing effect of 1–4 Gy IR in HAP-1 cells that express 1 copy of PRKDC (Supplemental Figure 8).