Dependence of DNA fragmentation time curve on cell lines. The VP-16 response was greater than taxotere for both cells lines, and the DU 145 response was greater than PC3 for both drugs. Whereas the DU 145 response peaks by 24 hrs and then subsides, the PC 3 response continues to increase for 44 hrs fluorescence intensity values for 1,000 cells were obtained for each sample. Mean endlabelling fluorescence intensity plots illustrate the effect of lengthening the antineoplastic treatment interval from 24 to 44 hrs (4A). Sample histograms show the fluorescence intensity distribution for untreated control cells (4B) and a 44 hours VP16 treatment of PC3 cells (4C). Note that in addition to shifting the main peak of the distribution toward higher intensity, a second "shoulder" population appeared between 50 and 500 units. The second shoulder population represents deterioration to smaller DNA fragments.