Fig. 4: GBP2 inhibits AKT phosphoactivation, and the PI3K/AKT pathway is involved in GBP2-induced cell death.

a The phosphorylation of different kinases was determined by western blot in GBP2 overexpressed or silenced K562 cells. GAPDH was used as a loading control. Representative blots (upper panel) and quantitative data (lower panel) from three independent experiments are presented (*P < 0.05; ***P < 0.001). b K562 cells were transfected with siRNAs as control or GBP2, followed by incubation with DMSO (0.3%), LY294002 (30 μM), U0126 (20 μM), or SP600125 (20 μM) for 24 h. Data presented are mean ± SEM of three independent experiments performed in triplicate. Asterisks indicate statistically significant differences (***P < 0.001). c The effects of AKT silencing on the viability of K562 and GBP2-depleted cells were determined at 24 h after the knockdown of AKT using siRNAs (200 nM). Data presented are mean ± SEM of three independent experiments performed in triplicate. Asterisks indicate statistically significant differences (***P < 0.001). d Phosphoactivation of AKT was assessed by immunoblot analysis in the GBP2 KO and HA-GBP2- or HA-GBP1-stably overexpressing K562 cell lines. GAPDH was used as the loading control. e The effects of LY294002 (30 µM) on cell viability were determined in GBP2 KO cell lines after 24 h of incubation. Data were shown as mean ± SEM of three independent experiments performed in triplicate. Asterisks indicate statistically significant differences (***P < 0.001). f K562 cells were transfected with siGBP2 (200 nM) for 24 h, followed by treatment with LY294002 (30 μM) for an additional 24 h. Western blot analyses using indicated antibodies were performed. Representative blots (left panel) and quantitative data (right panel) from three independent experiments are presented. Different letters denote statistically significant differences (P < 0.05).