Gfi-1B promotes proliferation of erythroblasts.

(A) Cell growth of transduced cells in liquid culture supplemented with cytokines as indicated. CD34⁺ cells were transduced with either empty vector (control) or Gfi-1B, or cotransduced with Gfi-1B and Bcl-xL. Results are shown as mean ± SD of triplicate cultures. (B) Flow cytometric profiles of transduced cells cultured for 10 days in the presence of indicated cytokines. Results are representative of 3 experiments. (C) Massive apoptosis of Gfi-1B–expressing erythroblasts. Apoptosis was detected by staining cells with PI and anti–Annexin V on day 10 of culture. Results are representative of 3 experiments. (D) Morphology of Gfi-1B–expressing erythroblasts. CD34⁺ cells transduced with Gfi-1B or cotransduced with Gfi-1B and Bcl-xL were cultured in the presence of the indicated cytokines. On day 10 of culture, glycophorin A⁺ erythroblasts were purified by cell sorting and subjected to morphologic analysis by May-Grüenwald-Giemsa staining. Original magnification × 1000.