Flow cytometry analysis and isolation of primary human bone marrow erythroblasts. CD45^- cells isolated from primary human bone marrow were stained with GPA, α4 integrin, and band 3. (A) Plot of band 3 vs α4 integrin of GPA⁺ cells. (B) Representative images of the sorted cells gated in A. (C) Proportions of distinct stages of erythroblasts in bone marrow shown in A. (D) Quantitation of the proportion of cells at each distinct stage of maturation after normalization based on total nucleated erythroid cells as 100% (N = 7).