Figure 3

Metformin and tamoxifen inhibit the colony-forming ability of MCF-7 and ZR-75-1 cells. The colony formation assays were performed as described in the “Methods”. (A, C, E and G) MCF-7 and ZR-75-1 cells were treated with 5 or 10 μM Tam, 5 mM Met, or 5, or 10 μM Tam + 5 mM Met. Typical cell colonies were imaged and are shown. (B, D, F and H) The number of colonies formed was counted for different groups. Histograms represent the quantification of the number of colonies formed. All data are expressed as the mean ± standard deviation (SD) for three independent experiments. *P < 0.05 for the 5 μM Tam group vs. the 5 μM Tam + 5 mM Met group; ^# P < 0.05 for the 10 μM Tam group vs. the 10 μM Tam + 5 mM Met group.