Inhibitors of Hsp90 and the proteasome result in different caspase cleavage patterns. Cells were treated with the IC₅₀ doses of each inhibitor (17-AAG, 5 μM; radicicol, 10 μM, and bortezomib, 8 nM) for a 24-hour treatment period, lysed and samples analyzed by immunoblotting. Representative cell line data on U266 are shown. All experiments were repeated in triplicate.