Metformin upregulates phosphorylation level of YAP1. A. SW480 and HCT116 cells were respectively incubated with 4 mM metformin for a short time: 0, 5, 15, 30, 60 and 120 min. B. The two kinds of cells were incubated for a long time: 0, 24 and 48 h. Data were presented as means ± S.D. (n=3), *P < 0.05.