The novel estrogen analog 17α-20Z-21-[(4-amino)phenyl]-19-norpregna-1,3,5(10), 20-tetraene-3,17β-diol (APVE₂) is shown minimized within the ligand binding pocket of both estrogen-receptor subtypes alpha (1ERE, blue) and beta (1QKM, orange). This molecule was chosen from a small library of 17α-modified-E₂ analogues originally designed for ER-β specificity. In a competition binding assay, APVE₂ was shown to exhibit moderate yet selective binding to ERβ. For details, see Mobley et al. in this issue.