Figure 2. Effect of the 125-bp (−1491 to −1366) segment on IGF1 promoter activity.

(a) After removal of the 125-bp segment located upstream of the STR, there was no significant difference among promoter fragments with different microsatellite repeat numbers. (b) When compared to full-length promoter fragments²⁹, removal of the fragment resulted in significant decrease of promoter activity in plasmids carrying low microsatellite repeat numbers (17 or 18 repeats). Relative luciferase activity is shown as mean ± SD. One-way ANOVA was used for group comparison (in a) and student’s t test was used for comparison of same STR repeat of two haplotypes (in b). Each assay was repeated four times in each of the four independent experiments (n = 16) (*p < 0.05; **p < 0.01 by student’s t test).