Flow cytometry is used to analyze the cell cycle and to determine the percent of apoptotic cells (in the sub-G1 phase). A–D) represent flow cytometry histograms of propidium iodide-stained cells displaying distinct cell cycle stages of untreated cells and treated cells with DTX, cat, and DTX + cat, respectively. E) Illustrates the mean values of the cells during sub G1, G0/G1, S, and G2/M phases.