Transduced CD34⁺⁺Lin⁻ UCB cells generate T cells expressing high levels of GFP in FTOC. Flow cytometric analysis of thymocytes recovered from FTOC initiated with transduced CD34⁺⁺Lin⁻ UCB cells that were not selected for GFP expression (in this experiment, 40% GFP⁺ cells at initiation of FTOC) before initiation of FTOC. After 35 days of culture, thymocytes recovered from FTOC were stained with IgG1 PE (not shown), IgG2a PE, CD1 PE, CD3 PE, CD4 PE, CD8α PE and analyzed by flow cytometry. Dot plots show forward scatter (FSC) and staining versus GFP expression of live, human cells recovered. The values in the crosses indicate the percentage of cells present in the corresponding quadrant. Quadrants were set to include 99.5% of the cells stained, with isotypic control antibody in the lower quadrants. The data shown are representative of six independent experiments.