Relative luciferase activities of 3'UTR constructs assayed in three different cell lines. Relative luciferase activity is calculated as the ratio of Firefly luciferase activity vs. Renilla luciferase activity. Three human cell lines (HEK293, HeLa and MCF7) were co-transfected with 0.8 μg of the Firefly luciferase plasmids (PGL3 basic, ERβpromPGL3, ERβpromPGL3ERβ1UTRG/A for rs4986938, ERβpromPGL3ERβ2UTRG/A for rs928554) and 0.02 μg Renilla luciferase plasmid as internal control, at 70% confluence in 24-well plates. Cells were harvested 24 h after transfection, and the activities of Firefly and Renilla luciferases were measured. Each measurement represents the average of three independent assays using independent plasmid preparations. Data are shown as mean ± SD. A. The luciferase activity of generated constructs in HEK293 cells, is normalized to the basic PGL3 plasmid, whose activity is set to 100%. The same results were obtained in the two other cell lines (data not shown); B. ERβ1 3'UTR polymorphism (rs4986938 G↔A);C. ERβ2 polymorphism (rs928554 G↔A). The luciferase activity of allele G is set to 100%.