Comparative analysis of the effects of SCF and FL. Ten thousand CD34⁺ CB cells were cultured for 10 days in serum-free medium supplemented with the basic cytokine combination TGF-β1 plus GM-CSF and TNFα. This cytokine combination was further supplemented with SCF and/or FL as indicated. Cells were analyzed by flow cytometry for CD1a expression as described in the Materials and Methods. Bars represent mean percentages ± SEM (left-hand side diagrams) and total numbers ± SEM (right-hand side diagrams), respectively, of cells with the indicated phenotypes observed in four experiments. The number of phenotypically defined cells was calculated from the percentage of cells showing the respective phenotype multiplied by the total number of cells in each culture.