Protein analyses were carried out according to a previously described method 29 (link). After drug treatment, cell lysates were prepared in ice-cold radioimmunoprecipitation assay buffer (25 mM Tris-HCl (pH 7.2), 0.1% sodium dodecylsulfate (SDS), 1% Triton X-100, 1% sodium deoxycholate, 0.15 M NaCl, and 1 mM EDTA). Protein concentrations were quantified using a bicinchonic acid protein assay kit (Pierce, Rockford, IL, USA). Proteins (50 μg/well) were subjected to SDS-polyacrylamide gel electrophoresis (PAGE), and transferred to nitrocellulose membranes. A rabbit polyclonal antibody against human HSP-70 purchased from Santa Cruz Biotechnology (Santa Cruz, CA, USA, dilution 1:500) was used to detect HSP-70. Cellular β-actin protein was immunodetected using a mouse monoclonal antibody against mouse β-actin (Sigma, dilution 1:2500) as the internal standard. The secondary antibodies used were horseradish peroxidase (HRP) anti-rabbit (Santa Cruz Biotechnology, dilution 1:2500) and HRP anti-mouse (Sigma, dilution 1:2500). After adding enhanced chemiluminescence substrates to react with these secondary antibodies according to the instruction of an enhanced chemiluminescence detection system of the Western Lightning Plus-ECL (Perkin Elmer), these protein bands were observed and quantified using a digital imaging system (UVtec, Cambridge, UK).