Characterization of Antp-TPR peptide-induced GB cell killing after induction of the erUPR. (A) Multiparametric flow cytometry. GB cells (U251, A172, and SN19) were incubated with or without Antp-TPR peptide for 18 h in the presence or absence of 0.1 μM Tg, and analyzed for annexin and propidium iodide (PI) staining. (B) The increase of cytotoxic activity of Antp-TPR peptide in the erUPR condition. GB and normal PE (ACBRI 515) cells were incubated with or without Antp-TPR peptide or 17-AAG (inset graph) at the indicated concentrations for 24 h in the presence or absence of Tg (0.05 μM), and cytotoxic activity was determined by WST-8 assay as described in the Materials and Methods section. Data represent the mean ± SD from experiments performed in triplicate. The single and double asterisks indicate P < 0.01 and P < 0.05, respectively. (C) Mitochondrial membrane potential. After treatment with or without Antp-TPR peptide in the presence or absence of Tg, GB cells were labeled with the mitochondrial transmembrane potential-sensitive fluorescent dye JC-1, and then images were taken using confocal laser scanning microscope as described in the Materials and Methods section. All scale bars are 50 μm.