HCT 116 cells were either left untreated, treated with 100 nM UCN-01 for 24 hours and 45 minutes, treated with 10 μM tachpyridine for 24 hours, or pretreated for 45 minutes with 100 nM UCN-01 followed by the addition of 10 μM tachpyridine for 24 hours. Cells were analyzed by flow cytometry. Shown are the means and standard deviations of 3 independent experiments.