The Gfi-1B zinc finger domain is essential for erythroid expansion.

(A) Schematic representation of Gfi-1B mutants. Zn indicates zinc finger domain; NLS, nuclear localization signal. (B) Mapping of the Gfi-1B domain responsible for erythroid expansion. CD34⁺ progenitors transduced with each Gfi-1B mutant were cultured in the presence of SCF and GM-CSF for 10 days, then analyzed by flow cytometry. (C) Schematic representation of Gfi-1 mutants. (D) Mapping of the Gfi-1 domain responsible for erythroid expansion. CD34⁺ progenitors transduced with each Gfi-1 mutant were cultured in the presence of SCF and GM-CSF for 10 days, then analyzed by flow cytometry.