Enumeration of colonies after cultivation of transduced CD34⁺Thy-1⁺ cells for 14 days in MC (CFU-C; A) or cultivation for 5 weeks on a mouse stromal cell line Sys1 followed by 14 days in MC (LTC-CFC; B). The number of CFU-C or LTC-CFC colonies is presented for 1 × 10³ or 1 × 10⁴ cells plated, respectively. The columns represent the mean values and the bars represent standard deviation of three independent enumerations. In some columns, the error bars cannot be plotted due to minimal data variation. Mock, transduction in the presence of IL-3, IL-6, and LIF but without viral supernatant; LIF, transduction in the presence of IL-3, IL-6, LIF, and viral supernatant; LIF (AZT), transduction in the presence of IL-3, IL-6, LIF, and viral supernatant and followed by cultivation of cells in MC or medium containing 10 μmol/L AZT; SCF, transduction in the presence of IL-3, IL-6, SCF, and viral supernatant.