Blocking protein synthesis impairs bortezomib-induced aggresome formation and BZ + SAHA–mediated apoptosis. (A,B) Cycloheximide blocks bortezomib-induced aggresome formation and apoptosis. Cells were treated with bortezomib in the presence or absence of 1 μg/mL cycloheximide for 24 hours. Aggresomes were quantified by confocal microscopy and apoptosis was measured by PI-FACS analysis. Mean (n = 3), SD. * indicates a significant difference from cells treated without cycloheximide, P < .05. (C,D) Knockdown of c-Myc using siRNA reduces BZ + SAHA–induced apoptosis. Myc expression was decreased in NCI-H929 cells as described in “siRNA transfection,” and immunoblotting was performed to confirm silencing of c-Myc and demonstrate associated decrease in HDAC6 expression. After exposure to c-Myc or nontarget siRNA, cells were treated with 5 nM BZ, 2 μM SAHA, or both agents, and apoptosis was measured by PI-FACS analysis. Mean (n = 3), SD. * indicates a significant difference from transfection with nontargeted siRNA, P < .05.