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 [16] 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).