TPP exhibits EA in a concentration–dependent manner. BG1Luc (A) or MCF-7 (B) cells were incubated with increasing concentrations of TPP and EA at CCi and EA determined as described under Material and Methods. Values are the mean ± SD of three wells (intra-assay “triplicates”) containing the same solution and are expressed as a percent of the maximal activity produced by E2 (%RME2). Solid black lines and data points show agonist activity for all data points not associated with toxicity (see Methods); red lines and data points show results of co-incubation of BG1Luc/MCF7 cells with TPP and 10-8 M ICI. Horizontal dotted line shows the 15%RME2 value that is significantly (p <0.01, Student’s T-test) greater than the VC and SC.