Normal cell cycle distribution of progenitors and stem cells. BM cells were harvested 4 weeks after induction, lineage depleted, and stained with anti–c-kit and anti-Sca1 antibodies. (A) Following fixation and permeabilization, cells were stained with anti-Ki67 and 7-AAD and analyzed by FACS to separate cells in different phases of the cell cycle, based on DNA content (7-AAD) and expression of Ki67. (B-C) Cell cycle distribution in knock-out and control mice of lin^–, c-kit⁺ cells (n = 4 per genotype; panel B) and LSK cells (n = 7 per genotype; panel C). Data represent means ± SDs, P > .7 for all parameters.