Adaphostin-induced Bcr/abl down-regulation is not affected by NAC. After 15 minutes of pretreatment with diluent (lanes 1-5) or 24 mM NAC (lanes 6-10), adaphostin was added to a final concentration of 0 (lanes 1 and 5), 1.25 (lanes 2 and 6), 2.5 (lanes 3 and 7), 5 (lanes 4 and 8), or 10 μM (lanes 5 and 10). Whole-cell lysates were prepared 8 hours later and subjected to SDS-PAGE followed by immunoblotting with antibodies that recognize c-abl (upper panel), phosphotyrosine (middle panel), or actin as a loading control (lower panel). In lanes 11-15, as controls, cells were treated with the proteasome inhibitor bortezomib (PS-341) at 50 nM in the absence or presence of 10 μM adaphostin, with 100 μM cycloheximide, or with 5 μM imatinib mesylate for 8 hours.