Regulation of proliferation during eosinophil differentiation by STAT5.

CD34⁺ cells were transduced with eGFP, STAT5a, or STAT5aΔ750. (A) The percentages of eGFP-positive cells were determined by FACS analysis after 7, 10, 14, and 17 days of differentiation. Results are expressed as averages ± SEMs of 5 individual experiments. (B) Proliferation was determined by counting the eGFP-positive cells. Results are expressed as -fold increases in cell numbers compared with day 7 as averages ± SEMs of 5 individual experiments. (C) Cells were transduced with either empty vector or STAT5aΔ750. The percentage of apoptotic cells in NGFR-positive cells was determined with Annexin V–FITC by FACS analysis. As a positive control for apoptosis, cells were preincubated for 1 hour with a cell-permeable Bim tat-peptide.