BFU-E growth in vitro and immunofluorescence staining of fixed and permeabilized patient's erythroblasts compared with healthy control. Healthy control (A) and the patient's (B) BFU-Es were grown in the presence of Epo, without Fe-SIH; the addition of 10 μM Fe-SIH rescued the growth of the patient's BFU-E (C). DMT1 (D) and TfR (E) were colocalized in EEA1–positive endosomes in the patient's erythroblasts. The expression of DMT1 in the patient's erythroblasts (F) was decreased compared with healthy control (G). Original magnifications: × 200 for panels A-C, × 1000 for panels D-G.