Figure 4: The HRE-mediated transcriptional activity induced by the 60 trial combinations in five iterations. The pHRE-Luc-transfected HEK293T cells were treated by the 60 trial combinations in five iterations, that is, 1–6, 7–12, 13–24, 25–42, and 43–60. The integer index of four flavonoids represented the corresponding concentration in each trial shown under each combination, that is, the index numbers of 0, 1, 2, 3, 4, 5 are corresponding to the final concentrations of 0, 0.016, 0.008, 0.4, 2, 10 μM. After 48 hours, the promoter-driven luciferase (pHRE-Luc) activity was determined. The response to mineral oil layering, a positive control, was as effective as in Figure 2(a). Values are expressed as the percentage of increase to basal reading (untreated culture) and in mean ± SD, where , each with triplicate samples.