Effects of SWT combined with tamoxifen on cell growth of MCF-7 (A) and MDA-MB-231 (B). The hormone-deprived cells in 96-well plates (5,000 cells per well) were treated with SWT and/or tamoxifen (TAM) for 48 hours, cell growth was measured with SRB assay. Results are expressed as percentage of control cells with no drug treatment. Points, means from three replicates; bars, S.D. *, P < 0.05; **, P < 0.01.