NFI-A overexpression favors differentiation and overcomes erythropoietin (Epo) dependence of erythroid (E) culture. (Ai) Growth curve of vector- and NFI-A–transduced HPCs in standard unilineage E culture (Epo 3 U/mL; mean ± SEM values; n = 3). (ii) Percentage of orthochromatic cells at sequential stages of E culture generated by vector- and NFI-A–expressing HPCs (mean ± SEM values; n = 3). (iii) Western blot showing ectopic expression of HA-tagged NFI-A in NFI-A–infected HPCs in E culture at day 8. (Bi) Growth curve (a representative experiment of 3 is shown) and (ii) morphologic evaluation (mean ± SEM values; n = 3) of E differentiation of vector- and NFI-A–transduced HPCs seeded in E culture with suboptimal amounts of Epo (0.15 U). (iii) Increase of GPA mean fluorescence intensity (MFI) (mean ± SEM values; n = 3) and real-time PCR showing β-globin mRNA expression (mean ± SEM values from 2 independent infections). (iv) Number of BFU-E colonies plated in Epo 0.15 clonogenic medium (mean ± SEM values of 2 paired experiments). (Ci) Growth curve of vector- and NFI-A–transduced HPCs in culture supplemented with minimal amounts of Epo (0.03 U). A representative experiment of 3 is shown. (ii) Percentage of GPA⁺ cells (left) and GPA MFI (right) at day 10. A representative experiment of 3 is shown. (iii-iv) Morphology analysis of vector- and NFI-A–infected HPCs (mean ± SEM values; n = 3).