Terminal erythropoiesis profiles of primary human bone marrow cells from MDS patients. CD45^- cells isolated from primary human bone marrow of 6 MDS patients, each with a different MDS subtype, were stained and analyzed, as described in Figure 5. Proportions of distinct stages of erythroblasts, after normalization based on total nucleated erythroid cells as 100%, are indicated. Panels A, B, C, D, E, and F show the terminal erythropoiesis profile of the MDS subtype refractory anemia, refractory anemia with ringed sideroblasts, refractory cytopenia with multilineage dysplasia, refractory cytopenia with multilineage dysplasia and ringed sideroblasts, refractory anemia with excess blasts-1, and refractory anemia with excess blasts-2, respectively. (I) proerythroblasts; (II) early basophilic erythroblasts; (III) late basophilic erythroblasts; (IV) polychromatic erythroblasts; and (V) orthchromatic erythroblasts.