Figure 1. HT-29 cells treated with 25 nM CPT are alive at 48 h and arrested in the G₂/M-phase of the cell cycle.

(a) Human colon carcinoma cells (HT-29) were treated with graded concentrations of CPT for either 48 h (◆) or 96 h (■) and viability was measured by the MTT assay. Results are mean±S.E.M. percentages of live cells for triplicate experiments. (b) Cells were cultivated with 25 nM CPT and prepared for analysis by flow cytometry at 24 and 48 h after treatments. Control cells (not treated) were also analysed. DNA content was determined by propidium iodide staining.