Phytoestrogens rhodoeosein and emodin isolated from F. convolvulus seed induce luciferase expression in human breast carcinoma SKBR3 cells transiently transfected with ERα or ERβ. ●= ERα-transfected SBKR3 cells; ○ = ERβ-transfected SKBR3 cells. Luciferase activity was normalized with protein concentration, was expressed as a percent of the maximum induction by E2 (10 nM), and was determined in cell lysates 24 h after treatment. Values represent the mean ± SD of triplicate determinations. Incubation of SKBR3 cells with 0.316 mM rhodoeosein caused cell death and was not included in the above analysis.