Figure 2.

Transfection and expression efficiency for IGF-I constructs. Data are presented as mean and SEs from three independent experiments. (A) Efficiency of transfection was determined in using the relative GFP expression compared with 18s as a housekeeping gene. Data are normalized to empty vector control that expresses only GFP. No statistical difference in transfection efficiency was found among any construct used in the study. (B) Efficiency of expression of the IGF-I cDNA insert for each plasmid was determined by the transcript copy ratio of the upstream IGF-I insert to the downstream GFP insert. Transcript copies were calculated from standard curves generated for each plasmid using the primer pairs listed in Table 1. Constructs GFP (empty vector control), IA (IGF-IA), IB, (IGF-IB), MI (Mature IGF-I/IGF-Istop), AK (IGF-IAK68G), BK (IGF-IBK68G), EA (SigEA), and EB (SigEB).