Cell cycle phase distribution analysis by flow cytometry in normal esophageal epithelial cells and esophageal cancer cells. A. The histograms show the cell cycle phase distribution, representative for 3 independent experiments. Note the increasing PI-staining/DNA content from EPC-hTERT cells to OE21, Kyse-410, OE33 and OE19 cells. Proliferating cells in red, apoptotic cells in green. B. The bar graph shows the distribution of cells in G0/G1-, S- and G2/M-phase of the cell cycle (mean and ± standard deviation of three independent experiments).