PPM1D-mutant cells have an abrogated apoptotic and cell-cycle response to chemotherapy. (A) Annexin V staining and flow cytometric analysis of Molm13 PPM1D-mutant and control single-cell clones exposed to 400 nM cytarabine or vehicle treatment of 24 hours. Data are shown as the means ± SD for biological replicates, and unpaired Student t tests were used for statistical analyses. (B) BrdU staining and flow cytometric analysis of Molm13 PPM1D-mutant and control single-cell clones after 24 hours of exposure to 100 nM cytarabine. Data are shown as the means ± SD for biological replicates and unpaired Student t tests were used to compare the cell-cycle progression in Molm13 PPM1D-mutant and control cells. (C-D) Molm13 PPM1D-mutant and control cells were exposed to cytarabine (0.25 µM) (C) or etoposide (0.5 µM) (D) for 16 hours. For each peptide, the cytochrome c release of the no-drug (DMSO)-treated cells are subtracted from the drug-treated samples to derive the drug-induced change in priming (percent δ priming).