Figure 2: DNA content (ploidy) analysis in non-small-cell lung carcinoma samples measured by the flow cytometric profile and analyzed by ModFit LT software. Cells prepared by the Hedley method  and stained with propidium iodide. (a) DNA histogram of diploid tumor. Note that a single G0/G1 population. (b) DNA histogram of aneuploid tumor. Observe the appearance of one separate second G0/G1 population to the right of the first G0/G1 peak. The percentage of cells in S-phase of cell cycle was calculated from each DNA histogram. In case of aneuploid histograms, percentage of cells in S-phase was only shown for aneuploid population. Note that DNA aneuploid tumors have higher SPF than DNA diploid tumors do (; Fisher's exact test).