Increased apoptosis in BM from 3-month-old NHD13 mice. (A) Hematocrit (HCT), red cell mean cell volume (MCV), and platelet and neutrophil counts of 3-month-old NHD13 mice (n = 5) and WT (WT) littermate controls (n = 5). (B) Proportions of annexin-V–positive and cleaved (ie, active) caspase-3–positive LKS cells from WT and NHD13 mice assessed by FACS (n = 3 of each genotype). (C) Representative FACS plots from cell-cycle analysis of WT and NHD13 LKS cells, and collated data showing cell-cycle distribution (G₀, G₁, and combined S/G₂/M) in WT (n = 6) and NHD13 (n = 4). * indicates G₀P < .05 difference from WT. (D) Representative FACS plots and proportions of FLK2+ LKS (n = 3 per genotype). (E) Numbers of granulocyte and macrophage colonies (CFU-GM), BFU-E, and megakaryocytic colonies (Meg-CFC) in BM from WT and NHD13 mice (n = 3 per genotype). (F) Giemsa stain of granulocytes colonies grown in semisolid agar demonstrating apoptotic bodies (arrows) in NHD13 granulocyte colonies. Error bars throughout represent the SEM (*P < .05; **P < .01; ***P < .001).