Expression of EF1α 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-EF-G-SI vector were significantly higher than those directed by the SINF-EF-G-I and SINF-EF-G vectors (P < .05, Student t test). In addition, the CV values of GFP fluorescence homogeneity obtained with the SINF-EF-G-SI vector (CV = 41 ± 6) were significantly better than those obtained with the SINF-EF-G vector (CV = 63 ± 41) (P < .05, Student t test).