ERG and ETS promote megakaryopoiesis in wild-type fetal liver progenitors. (A) Fetal liver cells transduced with MIGR1, MIGR1-ETS2, or MIGR1-ERG were differentiated for 72 hours and the GFP⁺ fraction was assessed for CD41 expression by flow cytometry. (B) The degree of polyploidization was determined by DAPI staining of GFP, CD41 double-positive differentiated fetal liver cells. (C) CD42 expression within the GFP-positive population was assessed by flow cytometry. Fold changes for CD41, percentage of cells with DNA content of 8N or more, and CD42 expression in the transduced cells relative to MIGR1 control-infected cells are shown to the right of the representative flow plots. Graphs display average fold changes plus or minus standard error. * P less than .02. For all experiments, n = 4. (D) qRT-PCR analysis of expression of genes that characterize megakaryocyte maturation in wild-type lineage-depleted fetal liver hematopoietic progenitors transduced with MIGR1, MIGR1-ETS2, and MIGR1-ERG. Data depict mean plus or minus standard error for a minimum of 3 independent experiments performed in triplicate. * P less than .05.