Cell death and proliferation of Nle-deficient HSCs and progenitors. (A and B) SLAM cells were stained with Annexin V/7AAD. (A) Quantitative results for dead and apoptotic cells and means (SD) are shown (n = 3 per genotype). (B) Representative FACS profiles are shown. This experiment was performed independently twice. (C and D) BM cells were stained for Ki67 and Hoechst 3 d after Cre induction. (C) The relative number of Ki67⁻ cells within the LSK CD34⁻ population is indicated (left; n ≥ 14 per genotype, pooled from three independent experiments), as well as the ratio (S-G2/M)/G1 among LSK CD34⁻ cells (right; n = 3 per genotype, from one experiment). Bars are means (SD). (D) Representative FACS profiles are shown. Note that Cre activation causes a reduction of Ki67⁻ LSK CD34⁻ cells in control compared with wild-type mice (not depicted). Similar results were obtained independently for LSK CD34⁻ and SLAM cells. (E) Levels of expression of cell cycle regulators in SLAM cells measured by RT-QPCR analysis. Bars are means (SD) of n = 4 mice; this experiment was performed twice. *, P < 0.05; ***, P < 0.0005.