Fig. 3

Responses of reporter gene assay yeast strains expressing ERα and ERβ (W303a and cwp1Δcwp2Δ) to synthetic estrogens. ERα and ERβ assay yeasts were exposed to EE2 (A), DES (B), PPT (C), and DPN (D). In the assay of these ligands, medium composition was changed from that used for other estrogen assays to reduce ligand-independent β-gal activity (data not shown, see Materials and Methods for details). Data represent the mean ± SD of triplicate experiments