Representative analysis of c-kit protein expression on CD34⁺⁺⁺ kit⁺⁺, kit⁺, and kit^Lo/− cells transduced withc-kit cDNA by flow cytometer. Sorted cells were prestimulated with 10% FCS and full dosage of IL-3, GM-CSF, IL-6, and Epo and transduced with c-kit cDNA (M5g hkit Neo) or mock (M5g Neo) control viruses as described in Materials and Methods. The cells were washed and incubated with the same cytokine combination for 48 hours and then stained with monoclonal CD117/PE (solid line) or mouse isotope control (dashed line) and analyzed by flow cytometer.