Megakaryocytes lacking GATA-1 show defects in both polyploidization and accumulation of cell mass. (A) Ploidy analysis of wild-type and GATA-1 KD bone marrow progenitors differentiated into megakaryocytes for 3 days. The cells were stained with anti-CD41 and DAPI to detect DNA content. Gates indicate the percentage of cells that is 8N or greater. One representative of 3 experiments is shown. (B) Cell size analysis of wild-type and GATA-1 KD cells within the 16N ploidy class were compared in a forward scatter–height histogram. The dotted line indicates the wild-type cells and the solid line, the GATA-1 KD cells. Mean FSC-A for WT and G1KD megakaryocytes was 740 and 668, respectively; confidence in difference is 99.9% based on Kolmogorov-Smimov test. One representative of 3 experiments is shown. (C) mRNA levels were determined by real-time quantitative RT-PCR of RNA isolated from wild-type and GATA-1 KD, BSA gradient–purified megakaryocytes. GATA-1 KD mRNA levels are shown relative to wild type, which were arbitrarily set to one. The means ± 1 SD are shown. Asterisks indicate P values determined by Student t test to be .05 or less. One representative of 2 experiments, each in triplicate, is shown.