Effects of the C/EBP-ϵ isoforms on eosinophil, erythroid, and neutrophil differentiation. CD34⁺ CB progenitors were transduced with retroviral vectors encoding each of the C/EBP-ϵ isoforms. After 72 hours of transduction, CD34⁺GFP⁺ cells were sorted by FACS, plated in Collagen Cult colony assays, and the cells induced to differentiate toward the eosinophil (A: culture in SCF, IL-3, and IL-5), neutrophil (B: culture in SCF, IL-3, and G-CSF), and erythroid (C: culture in SCF, IL-3, and EPO) lineages. The mean (± SD) number of GM, eosinophil, and erythroid colonies that developed from 750 plated CD34⁺GFP⁺ transduced progenitors is plotted for 3 independent experiments performed in duplicate or triplicate. The effect of the C/EBP-ϵ isoforms on plating efficiency is shown in panel D as the total number of hematopoietic colonies (myeloid + erythroid) developed from 500 plated CD34⁺GFP⁺ progenitors for each of the cytokine cocktails used to induce neutrophil (G-CSF), eosinophil (IL-5), and erythroid (EPO) colony formation. Statistically significant differences are shown for comparisons using 1-way ANOVA and LSD (*P ≤ .05, ***P ≤ .001).