Diminishing the levels of HDAC6 in leukemic cells not only reduces the binding of hsp90 to its client protein (Bcr-Abl) but also causes partial depletion of the client protein levels. (A) K562 cells were transfected with vector control or HDAC6 siRNA for 48 hours. After this, the cells were treated with 5 μM 17-AAG for 0, 8, and 16 hours and cell lysates were immunoprecipitated with anti-Abl antibody, and the immunoprecipitates were either immunoblotted with anti-hsp90 or anti-Abl antibody. (B) Alternatively, the cell lysates were immunoblotted with anti-Abl, AKT, or anti–c-Raf antibody. The levels of β-actin served as the loading control.