Frequency of human cell engraftment and LNGFR expression in NOD/SCID mice injected with transduced BM- or CB-derived CD34⁺ cells. BM- or CB-derived CD34⁺ cells were transduced with a GALV-pseudotyped LNSN retroviral vector and injected into sublethally irradiated NOD/SCID mice. The left panel shows the percentage of human cell engraftment (CD45⁺cells) 6 weeks after injection. The right panel shows the LNGFR expression in CD45⁺ cells obtained from the BM of engrafted animals. Each symbol represents one mouse.