Fig. 4. Enhancer activity of HUC1 and HUC2 in vitro. (A) Map indicating the regions tested in the cell transfection assay. Regions were cloned upstream of an SV40 promoter driving a firefly luciferase reporter gene. (B) Transcriptional activity of transfected constructs. The light emission obtained from the SV40 promoter alone was normalised to a value of 1. DMD, H19 differentially methylated domain; DMD^m, methylated DMD. HUC 1, HUC2 and both regions including the intervening sequence (HUC1+2) were tested. Maximum enhancer activity was detected from HUC1+2 (HUC1+2 with intervening sequence removed). Error bars show calculated standard error of the mean (s.e.m.) values.