Apoptosis, viable cell counts, and reticulocyte production of cultured erythroblasts from conditional bcl-x^-/- mice. (A) Percentage of TUNEL⁺ cells. (B) Viable cell numbers and (C) reticulocyte numbers from cultures of erythroblasts from conditional bcl-x^-/- mice with EPO (•) or without EPO (○) and of erythroblasts from bled littermate controls with EPO (▴) and without EPO (▵). Data are mean ± SEM of 3 (controls) and 7 (conditional bcl-x^-/-) independent experiments.