STAT5 knockdown impairs outgrowth of primitive CD34⁺ CD38⁻ cells. (A) Sorting scheme for obtaining single CD34⁺ CD38⁻ YFP⁺ (Renilla) or GFP⁺ (STAT5 RNAi) cells in 96-well format. NV indicates a nontransduced (no virus) control to set gates. (B) Percentage of wells quiescent or proliferating after STAT5 knockdown. Indicated percentages are averaged from 3 independent experiments. (C) Cell number per proliferating well at the indicated time points after sorting. Thirty individual wells per group are shown. Bars indicate average cell number with standard deviations at t = 100 hours. A Student t test was performed to calculate statistical differences between the 2 groups. N = 3. (D) The average number of daughter cells (offspring) produced per proliferating cell/well. A Student t test was performed to calculate statistical differences between the 2 groups. Error bars denote standard deviations; N = 3. (E) The average number of CFC colonies produced by proliferating cells per plate. A Student t test was performed to calculate statistical differences between the 2 groups. Error bars denote standard deviations; N = 3.