Homogeneous and long-term expression of the EGFP reporter gene by independent clones of Molt-3 cells transduced by the retroviral vector carrying the CD2 LCR.

(A) Target cells were transduced with the LESN or the LESNΔ-LCR retroviral vectors generated by transient transfection of 293T cells and selected in G418-containing medium for 4 weeks. After G418 selection, clones of both cultures were obtained by plating at low density (0.3 cells/well) and were analyzed for EGFP expression. MFI for each clone is indicated. (B) Long-term analysis of EGFP expression in vitro in the absence of G418 selective pressure by bulk cultures and representative LESN- or LESNΔ-LCR–transduced Molt-3 clones. (C) Southern blot analysis of proviral DNA shows independent and unique integration sites. Genomic DNA isolated from the clones was digested with XhoI/HindIII, which cut flanking cellular sequences and (once) the proviral DNA, upstream of the neoRgene, and was analyzed by Southern blotting with a probe for neoR.