Production of hematopoietic colonies. CD34⁺lineage^lo cells transduced with the indicated retrovirus were cultured in the presence of pokeweed mitogen-stimulated spleen conditioned media (A) or the indicated amount of human G-CSF (B). The total number of hematopoietic colonies (CFU-C) observed after 10 days of culture are shown. *P value < .05 compared with cultures of WT-transduced cells. Data represent the mean ± SD.