Molecular diversity of the cancer-cell-killing mechanism of Antp-TPR peptide and 17-AAG. (A) Time course of cell viability after the treatment with Antp-TPR peptide. GB (U251, A172, and SN19) and normal PE (ACBRI 515) cells were treated with Antp-TPR at the indicated concentrations, and then analyzed for cell viability by WST-8 assay. Data represent the mean ± SD from experiments performed in triplicate. (B) Induction of Hsp70 and Hsp90 by 17-AAG. GB cells were incubated with or without Antp-TPR peptide or 17-AAG for the indicated times, and extracts were examined by Western-blot analysis for expression of Hsp90, Hsp70, and Akt with their corresponding antibodies. β-Actin was used as the loading control. Bands were visualized by chemiluminescence. (C) Effect of Antp-TPR peptide and 17-AAG on transcription levels of Hsp27, Hsp70, and Hsp90 proteins. Total RNA isolated from GB cells treated with or without Antp-TPR peptide or 17-AAG at the indicated concentrations and time were reverse transcribed to cDNA, and then assessed by PCR (inset) or real-time quantitative PCR using specific primers as described in the Materials and Methods section. GAPDH served as an internal control.