Summary of gene transfer efficiencies into BM- and CB-derived CD34⁺ cells. Gene transfer efficiencies into hematopoietic cells (total cells), CD34⁺ cells, or CFC were estimated by FACS (total cells and CD34⁺) or immunostaining techniques (CFC). Data from LNSN-transduced cells (circles) and mock transduced cells (squares) are presented. Black symbols: BM-derived CD34⁺ cells, open symbols: CB-derived CD34⁺ cells. Each symbol represents a single experiment.