Genetic depletion of Ent1 in mice hampers erythroid lineage commitment in the BM. (A) Increased size of RBCs in Ent1^−/− mice compared with WT mice. EDTA-anticoagulated mouse blood was used for Wright-Giemsa staining and representative blood smears are shown. (B) Schematic of MEP, CMP, and GMP progenitors as well as the differentiation to mature red cells and granulocytes. The flow cytometry-based analytic strategy to identify the different populations is presented. (C) Representative FACS analysis of hematopoietic progenitor cells of BM of 8- to 12-week-old Ent1^−/− and WT mice. The number of Lin⁻cKit⁺, CMP, MEP, and GMP cells per 10⁶ BM cells (excluding RBCs) are presented in WT and Ent1^−/− mice (n = 9, *P < .05). (D) Erythroid and myeloid cells were evaluated as a function of Ter119 and Gr-1 staining, respectively, and representative dot plots are shown (left). Quantification of the percentages of Ter119⁺ cells vs Gr-1⁺ cells in BM of Ent1^−/− and WT mice are presented (right) as means ± standard error of the mean (SEM) with each point corresponding to data from 1 mouse (*P < .05). (E) Quantification of spleen body weight ratio in Ent1^−/− and WT mice (*P < .05). (F) Representative FACS analyses of differentiated erythroblasts by CD71 and Ter119 staining in spleens of Ent1^−/− and WT mice (left). The developmental stage of erythroblasts was indicated by populations I, II, III, and IV. The quantification of these populations is displayed on the right (*P < .05). (G) Representative FACS plots are shown for splenic Ter119⁺ cells vs Gr-1⁺ cells in Ent1^−/− and WT mice (left) and quantification of data in individual mice are presented as means ± SEM (right; *P < .05). (H) Biotin-labeled RBCs in WT (black circles) and Ent1^−/− (red squares) are shown as a function of time after biotin labeling. Means ± SEM of 5 mice in each group are shown.