FACS profiles of glycophorin A⁺ cells obtained directly from fetal liver, cord blood, and adult marrow or from directly plated 12- to 14-day-old erythroid colonies generated in methylcellulose assays of human fetal liver, cord blood, or adult marrow cells or from human CFU-E/BFU-E produced in NOD/SCID mice engrafted for 6 weeks with human fetal liver, cord blood, or adult marrow cells. Harvested cells were stained with anti-glycophorin A and anti-Hb antibodies as described in the Materials and Methods. Note that the intensity of staining with the 2 different anti-Hb antibodies provide only a relative measure of the amount of HbA and HbF in each cell and therefore cannot be used to compare absolute HbA and HbF expression levels.