DNA sequences encompassing HS10 specify transcriptional enhancer co-activator activity. A, Schematic diagram of lucifierase reporter gene constructs (labeled numbers 1–5, respectively). B, The luciferase activities of the above constructs was measured after transient transfection into the indicated cell lines. Data are representative of several independent experiments and are plotted as the activity of each construct relative to the activity of κpLuc after correction for the relative transfection efficiencies by monitoring the activity of a co-transfected pRL-CMV Renilla luciferase reporter gene. Data are presented as means ± SD. Statistical significance was determined by a paired Student’s t test. Double and single asterisks indicate p<0.01 and p<0.05, respectively, relative to the activity exhibited by the κpLuc construct.