EGFP expression in myeloma and nonmyeloma cell lines. The cell lines tested were transduced and expressed EGFP to different extents. (A) The percentage of cells expressing EGFP after transduction with the CMV (▪) and KIE (▦) vectors (mean of 3 experiments ± 1 SD). (B) The change in mean fluorescence of cells transduced with the 2 vectors compared with controls. While the CMV promoter/enhancer led to EGFP expression in virtually all cell lines tested, EGFP expression from the KIE vector was restricted to the myeloma cell lines. The 2 vectors were statistically equivalent in myeloma cells (error bars indicate SD;P = .1797).