Additional file 2: Figure S2. The effect of different concentrations of metformin in ovarian cancer cells. Tumor proliferation (2D-colony formation) of mouse ovarian cancer cells treated with different concentrations of metformin. Maximum plasma concentrations (Cmax) of Metformin was clinically around 1.03–4.12 mg/L ( https://www.accessdata.fda.gov/drugsatfda_docs/label/label/2008/020357s031 ,021202s016lbl.pdf).