FACS analyses of the transduction, selection, and expansion process. eGFP expression and percentage of positive cells of SIN- and LTR-transduced BM cells 1 day after the second transduction (top panel), after 2 weeks (middle panel), and after selection of a single clone (bottom panel). Representative data obtained in experiment 3 and experiment 4 (FACS analysis of the SIN vector-transduced clone).