NEIL1-editing enhances double-stranded DNA damage repair responses. (A) Cell viability of NEIL1-WT and NEIL1-edited KMS12BM when treated with increased doses of melphalan for 48 hours. (B) Western blot analysis of protein expression profile of various DNA-damage-repair factors in NEIL1-WT and NEIL1-edited cells. (C) Cell viability of NEIL1-WT and NEIL1-edited cells when exposed to treatment of either etoposide (5 μM), melphalan (5 μM), or a combination of both for 48 hours. Untreated cells were vehicle (phosphate-buffered saline) control. (D) Cell viability of NEIL1-WT and NEIL1-edited cells when exposed to a combination of etoposide (5 μM) and increased melphalan concentration (5, 10, 15, 20 μM) for 48 hours. (E) Cells were incubated with etoposide (5 μM), melphalan (5 μM), or a combination of both for 48 hours, and apoptosis was measured with Annexin-V assay. Percentage specific apoptosis was calculated with the formula of % specific apoptosis = (treated−untreated)×100/(100−untreated), as previously reported.²  (F) Western blot analysis of phospho-H2AX expression after the cells were subjected to either etoposide (5 μM), melphalan (5 μM), or a combination of both for 48 hours. **P < .05; ***P < .001.