Sp3-deficient erythroid cells display a cell-autonomous differentiation defect. (A) The number of BFU-Es and CFU-Es per E12.5 and E14.5 fetal liver was determined for embryos with the indicated genotypes and gestational ages. The values in wild-type embryos were set at 100%. (B) Abundance of BFU-Es and CFU-Es in E12.5 and E14.5 Sp3-deficient embryos corrected for the cellularity of fetal livers. Wild-type values were set at 100%. (C) Fluorescence-activated cell sorter (FACS) analysis of fetal liver cells that were allowed to differentiate in vitro during 0, 2, and 3 days, using the suspension culture system. As the cells progress through maturation, they become smaller. Enucleated cells with small FSC values (lower than 360, as indicated) appear during culture at days 2 and 3.