(A–F) HeLa cells were transfected with control non-targeting siRNA (A, D), PTPMT1 siRNA#1 (B, E), or PTPMT1 siRNA#2 (C, F) for 96 hours. Cells were collected and stained for cleaved caspase-3 (top panels) or cleaved PARP (bottom panels) under each condition, with positivity indicated as an increase in fluorescence on the FACS histogram (lower right quadrant). (G–I) HeLa cells were transfected with control, PTPMT1, and/or BAX/BAK siRNAs for 96 hours. Cells were collected and stained for cleaved caspase-3 (G, H) or propidium iodide positivity (I). Error bars indicate standard deviation of three experiments. Statistical significance was calculated using a student’s t test; * - p<0.05; ** - p<0.01; *** - p<0.001.