Viability of MCF-7 cells incubated with different concentrations of E2 (A), different concentrations of B combined with 0.1 µM Tamoxifen (B), different concentrations of C combined with 0.1 µM Tamoxifen (C), different concentrations of I combined with 0.1 µM Tamoxifen (D). Mean values from three independent experiments ± SD are presented. Significant alterations are expressed relative to control cells (marked with asterisks). Statistical significance was at * p < 0.05, ** p < 0.01, *** p < 0.001. Different letters indicate statistical differences (p ≤ 0.05) between treatments estimated by Tukey’s test.