Transduction of Mpl-R in colonies grown with TPO alone. Representative PCR analysis performed on cell lysates of individual colonies with primers specific for the retroviral Mpl-R gene (6 BFU-E and 16 CFU-GEMM). Colonies were generated from hematopoietic cells cocultured on GpE86-Mpl-R cells and grown in methylcellulose in the presence of TPO without G418. Controls were the cell lysates of uninfected FDC-P1, or a population containing 50% (50) or 100% (100) of Mpl-R–infected FDC-P1 cells.