Hydroxamic acid analogues induce acetylation of hsp90 and hsp70. (A) K562 cells were transfected with control or siHDAC6 constructs. After 48 hours, they were exposed to the indicated does of LBH589 for 16 hours and immunoblotted for HDAC6, acetyl-tubulin, or β-actin. (B) After 48 hours of control vector or siHDAC6 transfection and indicated exposure to LBH589, hsp90 and hsp70 were immunoprecipitated and immunoblotted for acetyl lysine or indicated chaperone/cochaperone. (C) K562 and HL-60 cells were exposed to the indicated concentrations of LAQ824 for 16 hours. After this, hsp90 was immunoprecipitated from the cell lysates and immunoblotted with either anti-hsp90 or anti–acetylated lysine antibody. (D) The cell lysates from K562 cells expressing HDAC6 siRNA or from untreated or LBH589-treated K562 cells were immunoprecipitated with anti-Abl antibody, and the immunoprecipitates were immunoblotted with antiubiquitin. The blot was stripped and immunoblotted with anti-Abl antibody. (E) The cell lysates were immunoblotted with anti-Abl or anti–c-Raf antibody. The levels of β-actin served as the loading control.