Asxl1 loss leads to increased apoptotic and mitotic cells in BM Lin^–c-Kit⁺cells. (A) Flow cytometric analysis of freshly isolated Lin^–c-Kit⁺ cells from the BM of representative WT, Asxl1^+/−, and Asxl1^−/− littermates (5 weeks old) after Annexin V/7-AAD staining. (B) Quantitation of the subgroup of apoptotic cell population that is Annexin V⁺/7-AAD^–. Data are presented as mean ± SD from 3 sets of WT, Asxl1^+/−, and Asxl1^−/− mice (4-5 weeks old). (C) Cell cycle analysis of Lin^–c-Kit⁺ cells from representative WT, Asxl1^+/−, and Asxl1^−/− littermates are shown (5 weeks old). Similar results were obtained using another set of Asxl1 littermates of mice (4 weeks old). (D-E) Representative images of May-Giemsa–stained cytospin preparations of cells from WT, Asxl1^+/−, or Asxl1^−/− BM cell–derived colonies showing an increased proportion of mitotic cells (red arrowheads, D). The quantitation of the percent of mitotic cells is shown by performing a 500-cell count of at least 10 colonies from each genotype (E). Representative data from 2 separate experiments are shown as mean ± SD. *P < .05, **P < .01.