Reduced NUDT15 expression increased sensitivity to 6-MP–induced DNA damage. (A) Schematic diagram of experiments. (B) Relative expression of the NUDT15 gene in PSC-derived hematopoietic progenitor cells (HPCs). Relative quantity (RQ) values were calculated via the ΔΔCt method using multiple control genes in wild-type (WT) cells as an internal control in Kh1 and B7 strains. (C) Cell numbers after exposure to 6-MP. (D-E) Representative fluorescence-activated cell sorting panel and median fluorescence intensity of pH2AX levels after exposure to 6-MP. *Significant difference (P < .05) in both the Kruskal-Wallis test and post hoc comparison, **significant difference only in the Kruskal-Wallis test. ESC, embryonic stem cell; iPSC, induced pluripotent stem cell; n.s., no significant difference in Kruskal-Wallis test; sc, scrambled; sh, short hairpin.