Figure 4. Promoter Activity of the mNaip LTRs.

The ORR1E LTRs for each copy were cloned into a modified pGL3B vector and tested for luciferase activity in the MS1 cell line. pGL3B and pGL3P, containing a SV40 promoter, were used as negative and positive controls, respectively. Luciferase activity was normalized relative to the cotransfected Renilla luciferase control and then to pGL3B to demonstrate fold activation. Each bar represents the mean of at least four independent transfections ± SEM.