Objective To investigate the effects of metformin on the proliferation and apoptosis of human oral cancer cell line KB in vitro.Methods Human oral cancer cell line KB was exposed to different doses of metformin(0,1.25,2.5,5,10,and 20 mmol/L),and the changes in cell viability were detected using MTT assay.Colony formation of the cells was observed following an 8-day metformin exposure.The changes in mitochondrial membrane potential were measured by JC-1 assay,and PI staining was used to observe the cell apop...