(A) Transduction of leukemia cell lines with HIV-1–based lentiviral vectors. Transduction of Nalm-6 and Reh cells with the lentiviral vector pHR′-CMV-EGFP. (Left panels) untransduced cells; (right panels) transduced cells; (upper panels) Nalm-6 cells; (lower panels) Reh cells. (B) Comparison of retroviral- and lentiviral-mediated gene transfer in leukemia cell lines on (▧) fibronectin (50 μg/mL) and (▪) BSA (2%).