Examples of integration and expression of transducedc-kit cDNA by PCR (A) and RT-PCR (B) analysis. Sorted single CD34⁺⁺⁺kit⁺⁺ and kit⁺cells were prestimulated, transduced with c-kit cDNA or mock control viruses, and growth in the presence of cytokine combination as described in Materials and Methods. Individual BFU-E colonies were removed and DNA and RNA were extracted for PCR and RT-PCR analysis. The PCR generates a 959-bp fragment.