Fig. (5) Renilla reporter expression parallels compound cytotoxicity. High concentrations of E2 have an effect on cell viability. HEK293 cells were transiently co-transfected in 96-well plates with ERα-LBD/ 5X luc2P vectors. 24 hours post transfection, 1:2 serial dilutions of E2 was added to the respective wells. An another plate was prepared in parallel and measured with CellTiter-Glo® Luminescent Cell Viability Assay. Firefly and Renilla luciferase activities were measured using the Dual-Glo^™ Assay System. Firefly reporter expression (Fluc), Renilla reporter expression (Rluc) and CellTiter-Glo® Luminescent Cell Viability Assay Luminescence (cytotoxicity) shown as induction, ave. treated/ave. untreated.