Figure 1: Effect of Hoechst 33342 concentration on the viability of IEC-6 (a) and U-937 cells (b). Both cell types were treated with different concentrations of Hoechst 33342 (0 to 5 μg/mL) for up to 7 days. Cell viability was then determined by using the MTT assay. The data are expressed in terms of the percentage of viable cells relative to control cells, which were treated with medium only.