EBs generated ex vivo by MNCs of PV patients with or without dexamethasone express levels of GATA1, NF-E2, and WT1 similar to those expressed by EBs generated by MNCs from NDs with dexamethasone. Maturation profiles (by FACS analysis for CD36/CD235a expression; A,C) and gene expression profile (GATA1, GATA2, and β-globin; B,D) of EBs obtained from NDs in the presence of growth factors (GFs) without (A-B) or with (C-D) dexamethasone (DXM). Because of the great contamination from non-EBs (> 50%; Figure 1C and Table 1), EBs generated in the absence of DXM were purified by sorting into classes of progressively more mature populations on the basis of CD235a expression (CD235a^low, CD235a^medium, and CD235a^high), and gene expression by individual populations was compared. Erythroblasts obtained in the presence of GFs plus DXM were analyzed before and after induction of maturation with erythropoietin (EPO) for 48 hours. Expression levels are expressed as 2^−ΔCt and are presented as mean ± SD of at least 3 separate experiments. (E) Levels of GATA1, GATA2, NF-E2, WT1, and β-globin expressed by EBs generated by heterozygous (top panels) and homozygous (middle panels) PV patients and by NDs (bottom panels) with and without DXM. Because of the heterogeneity of their cell composition, samples from NDs cultured without DXM were not included in the analyses. Expression levels are presented as 2^−ΔCt and as mean ± SD of different experiments. If differences were significant, P values are provided. Erythroblasts obtained from heterozygous PV patients with DXM expressed levels of GATA2 and β-globin significantly different from those expressed by EBs obtained from NDs with DXM and are indicated in red. The numbers of experiments included in each group are indicated by n.