Metformin enhances the inhibitory effect of cisplatin on cell migration and invasion. A, B. SKOV3 and Hey cells were divided into four groups: the control group, metformin group (20 mM), cisplatin group (1.6 µg/ml) and metformin + cisplatin group (20 mM metformin + 1.6 µg/ml cisplatin). Transwell assays were used to measure cell migration after 24 hours of treatment. C, D. SKOV3 and Hey cells were divided into four groups: the control group, metformin group (20 mM), cisplatin group (1.6 µg/ml) and metformin + cisplatin group (20 mM metformin + 1.6 µg/ml cisplatin). Transwell assays were used to measure cell migration after 48 hours of treatment. *, P<0.05, **, P<0.01, and ***, P<0.001.