CB CD34⁺ cells with up-regulated hTERT expression contained similar frequency of colony-forming progenitor cells as the CD34⁺ bulk cells. Sorted dGFP⁺ (▪), GFP⁺ cells (▦), and mock-transduced cells (□) were plated into methylcellulose medium supplemented with cytokines at 500 cells/mL/plate, as described in “Materials and methods.” Similarly, the sorted CD34^–CD15/33⁺ cells were plated at 5000 cells/mL/plate (▨). The content of BFU-E, CFU-GM, and CFU-GEMM cells was scored 2 weeks after plating according to standard criteria. The averages and standard deviations of colony numbers per plate from 3 independent experiments are shown.