Total RNA was isolated from MCF-7 cells, reverse-transcribed into cDNA and subjected to realtime RT-PCR analysis for quantitation. Treatment on MCF-7 cells was as follows: DMSO (vehicle), daidzein, 2, 3a, E2, daidzein + E2, 2 +E2, 3a + E2 (10 μM and 10 μM + E2). Results are expressed as the mean unit ± S.E.M. (***p < 0.05; **p < 0.01; *p < 0.001) with significant differences from vehicle control.