TP53 and lung cancer: These inhibitory effects of metformin were not specific to HCT116 p53−/− cells as metformin inhibited oxygen consumption and cellular proliferation of Control-HCT 116 p53+/+ cells and Control-A549 human lung cancer cells but not NDI1-HCT 116 p53+/+ or NDI1-A549 cells (Figure 2—figure supplement 1 and 2).