<p><b>Chemical structure (A) and cell-proliferation assay (B) for lignans.</b> (<b>A</b>) The phenylpropane backbone is shadowed. (<b>B</b>) MCF-7 cells were treated with vehicle (dimethylsulfoxide, DMSO), E<sub>2</sub> (10 nM) or different concentrations of chemicals as indicated: 1, 1 nM; 2, 10 nM; 3, 100 nM; 4, 1 μM; 5, 10 μM; and 6, 100 μM (on the left), and 10 μM EL (on the right). After incubation for 72 h, cell proliferation was examined by sulforhodamine B (SRB) assay. The rates of cell proliferation in response to E<sub>2</sub> or lignans to that of a control (DMSO) are shown in the graph. *: <i>p</i> < 0.05; vs. control (C), #: <i>p</i> < 0.05; vs. E<sub>2</sub>, or §: <i>p</i> < 0.05; vs. EL. ICI: ICI 182,780, an ER antagonist.</p
