Flow cytometric histograms for DiOC₆ and apoptotic probes in the TP53 temperature-sensitive mutant 4G5 cell line cultured at the permissive temperature (32°C) for 9 and 18 hours.

At 9 hours, few DiOC₆-low (depolarized, plot i) or PI-low (sub-G₀, plot ii) cells were apparent. At 18 hours, DiOC₆-low (depolarized cells, plot iii) were observed. PI-low sub-G₀ cells were also found at this time (plot iv) but in a smaller proportion of cells than had depolarized. These results are representative of 5 similar experiments. Dual staining with DiOC₆ and the vital dye 7-AAD (plot v) showed a subset of cells that had depolarized but were impermeable to 7-AAD (lower left quadrant), indicating that loss of MTP preceded loss of membrane integrity in the apoptotic process.