Figure 5.

As^III antagonizes the TAM-dependent inhibition of proliferation. MCF7 cells and MCF7 cells pre-treated for 6 weeks in the presence of 1 µM NaAs^III (MCF7NaAs^III) were cultured for 72 h in control DMEM, or DMEM plus E2 (10 nM), TAM (1 µM), or their combination. (A) Bars represent the means ± SEM of quantitation (fold-change of DMEM Control) of proliferation determined by MTT assay from 2 separate experiments (n=2) with 5 replicates. (B) Bands are representative immunocomplexes for BRCA-1, ERα and internal standard GAPDH from 2 (n=2) separate experiments performed in duplicate. (C) Bars represent the means ± SEM of percentage cells in S-phase measured by flow cytometry from two separate experiments (n=2) with 5 replicates. In (A) and (C) different letters represent statistically significant multiple comparison (a>b>c, etc.) differences (P<0.05). As^III, trivalent arsenite; BRCA1, breast cancer 1; NaAs^III, sodium arsenite; TAM, tamoxifen; E2, 17β-estradiol.