Expression of MU3 promoter–containing lentiviral vectors in KG1a clones. (A) FACS analysis of GFP expression of single-copy clones that were identified in Figure 3 after culturing for 2 months. (B-C) Comparison of MFI values of GFP fluorescence of the single-copy KG1a clones. *The MFI values of GFP fluorescence directed by the SINF-MU3-GW-SI vector were significantly higher than those directed by the SINF-MU3-GW-I vector (P < .05, Student t test). In addition, the CV values of GFP fluorescence homogeneity obtained with the SINF-MU3-GW-SI vector (CV = 46 ± 7) were significantly better than those obtained with the SINF-MU3-GW vector (CV = 88 ± 56) (P < .05, Student t test). In panel C, thick horizontal bars represent average MFI values of GFP fluorescence as indicated by the number above each column of data points, which are denoted by individual circles.