Apotransferrin decreases TfR1 and enhances enucleation in β-thalassemic erythroid precursors. (A) Protein concentration for TfR1 in CD45 negative bone marrow cells from WT, th3/+, and apotransferrin treated th3/+ mice. (B) Statistical analysis of TfR1/β-actin (n = 4-5 mice per group). (C) Protein expression of TfR1, pStat5, Stat5, Irp-2, and β-actin in fetal liver cells treated with apotransferrin in vitro (experiment repeated twice). (D) Statistical analysis of TfR1/β-actin in fetal liver cells treated with apoTf in vitro. (E) Proportion of TfR1 on extruded nuclei in relation to reticulocytes during in vitro enucleation of th3/+ fetal liver cells with and without additional apotransferrin (n = 6 pups per group). (F) Erythroid enucleation in WT, th3/+, and apotransferrin-treated th3/+ fetal liver cells (n = 3-4 pups per group). *P < .05; **P < .01 vs WT mice; †P < .05; ††P < .01 vs th3/+ mice. Ext nucleus, extruded nucleus; retic, reticulocyte; MFI, mean fluorescence index.