KIT signaling is dispensable for mast cell progenitor survival. (A-C) CD34⁺ progenitors were enriched from buffy coats, cultured for 5 days, and analyzed by flow cytometry. The medium was supplemented with imatinib dissolved in dimethyl sulfoxide where indicated. Vehicle indicates that the medium was supplemented with dimethyl sulfoxide only. (B) The fraction of CD117^hiFcεRI⁺ pre–mast cells from panel A was normalized to the combined IL-3, IL-6, and vehicle condition for each buffy coat (n = 3). The bars represent the means ± SEM. (C) The CD117 expression on CD34⁺ cells from day 5 was quantified by calculation of the median fluorescence intensity. The expression level of CD117 is shown as a percentage of the IL-3, IL-6, and vehicle condition. The bars represent the means ± SEM of 3 buffy coats. Live singlet cells are shown in the flow cytometric graphs. All statistical analyses were performed using 1-way ANOVA with Tukey’s multiple comparisons test. *Adjusted P < .05; **adjusted P < .01; ***adjusted P < .001; ****adjusted P < .0001.