Progenitors from c-myb^KD/KD fetal liver display retarded commitment and progression through erythropoiesis. Fetal liver single-cell suspensions from E14 c-myb^+/+ and c-myb^KD/KD embryos were stained with α-CD71(FITC), α-CD41(PE), α-c-Kit(PE-Cy5), and α-TER119(APC). CD41^– live cells were sorted based on their CD71 and c-Kit staining. (A) Cells in sorting regions 1-4 (top panel) are displayed in the corresponding color in the middle and bottom panels to indicate their TER119 expression pattern. Note that a minor shift in the TER119 signal of c-myb^KD/KD cells is attributed to overcompensation caused by reduced c-Kit levels (see panel B). (B) Sorted cells were cultured in SP34 medium containing SCF (100 μg/mL), EPO (2 U/mL), and dexamethasone (1 μM). At the indicated time points, cells were stained with α-CD71 (FITC) and α-TER119 (APC) and analyzed by flow cytometry. Panels Bi to Biv show the development of cells from CD71/c-Kit–sorted regions 1 to 4 (A), respectively. Percentages in Biii and Biv represent proportions of cells at the CFU-E stage. Dead cells were excluded by propidium iodide staining. All plots are in log-scale.