Depletion of HDAC2 sensitizes cells to epirubicin-induced apoptosis. Depletion of HDAC2 sensitizes cells to epirubicin-induced apoptosis. A, Western blot showing select depletion of HDAC1, HDAC2, and HDAC6 by siRNA in MCF-7 (top), T47D (middle), and MDA-MB-468 (bottom) cells. B, comparison of epirubicin-induced apoptosis in cells transfected with nonsilencing siRNA versus cells depleted of HDAC1, HDAC2, or HDAC6 in MCF-7 (top), T47D (middle), and MDA-MB-468 (bottom) cells. As a positive control, cells transfected with nonsilencing siRNA were treated with 2 mmol/L VPA for 48 h before 0.5 μmol/L epirubicin for 4 h. The presence of apoptotic nuclei was evaluated 24 h after epirubicin treatment. Significance was by Student's t test. Bars, SE from a minimum of three replicate experiments. Douglas C. Marchion et al. Mol Cancer Ther 2009;8:794-801 ©2009 by American Association for Cancer Research