Effects of the C/EBP-ϵ isoforms on myeloid and erythroid lineage colony formation. CD34⁺ CB progenitors were transduced with retroviral vectors encoding the C/EBP-ϵ isoforms and after 72 hours of transduction, CD34⁺GFP⁺ cells were sorted by FACS and cultured in semisolid Collagen Cult (StemCell Technologies) colony assays using cytokines to drive differentiation of mixed myeloid lineages excluding erythroid (A: culture in SCF, GM-CSF, IL-3, and IL-5), or both mixed myeloid and erythroid lineages (B: culture with SCF, GM-CSF, IL-3, IL-5, and EPO). The mean (± SEM) number of granulocyte-macrophage colony-forming unit (CFU-GM), granulocyte-erythrocyte-macrophage-megakaryocyte colony-forming unit (CFU-GEMM), and BFU-E colonies that developed from 750 plated CD34⁺GFP⁺ transduced progenitors is plotted for 3 or 4 independent experiments performed in duplicate or triplicate. Statistically significant differences of interest are shown (brackets and P values) for comparisons using 1-way analysis of variance (ANOVA) and least significant difference (LSD).