KLF4 induces cell-cycle arrest/delay and death that is nonredundant with imatinib. (A) v-Abl–transformed cells were harvested at 48 hours after infection and stained for hCD4 and annexin V for FACS analysis. The percentages of death in marker-negative and -positive cells are displayed in the top left and right quadrants, respectively. Data are representative of 3 to 5 experiments. (B) v-Abl–transformed cells were infected and harvested as in panel A and then stained for marker and propidium iodide to measure cell cycle. Percentages of G₁, S, and G₂/M were calculated from a live cell gate, with apoptosis calculated as the fraction of total cells with subdiploid DNA content. Data are representative of at least 5 experiments. (C) v-Abl–transformed cells were stained with CFSE, infected with indicated retroviruses, and analyzed by FACS 24 hours after transduction. The gray shaded trace represents the population that is negative for the marker gene while the darker line represents cells that have been infected and express the marker. Data are representative of 3 experiments. (D) v-Abl cells were incubated with the indicated concentration range of imatinib 24 hours after transduction with MIC or MIC-KLF4 and then stained with annexin V 24 hours later for analysis by FACS. Representative plot from 2 experiments is shown and error bars represent SD.