Increased apoptosis in Stat5a^−/−5b^−/− bone marrow erythroblasts.

Bone marrow from either wild-type or Stat5a^−/−5b^−/− mice was labeled with CD71 (APC channel) and Ter119 (PE channel) as described in Figure 4. Cells were then incubated with FITC-conjugated annexin V and propidium iodide and analyzed by flow cytometry. Cells positive for propidium iodide were excluded from analysis. The top and bottom left-hand panels show flow cytometry density plots for CD71 and Ter119 similar to those shown for spleen cells in Figures 4 and 5. The right-hand panels show density plots for annexin V binding on Ter119^high cells only. The region of increased annexin V binding is indicated and contains 0.4% of wild-type Ter119^high cells (top right-hand panel) and 8% of Stat5a^−/−5b^−/−Ter119^high cells (bottom right-hand panel). Data shown are representative of 2 experiments.