Coadministration of Bay 11-7082 and UCN-01 results in the cleavage of Bcl-2 and the down-regulation of Bcl-x_L, Mcl-1, and XIAP in MM cells. MM cells were exposed to 200 nM UCN-01 ± 4 μM (A; U266) or 1 μM (B; MM.1S) Bay 11-7082 for 24 hours, after which cells were lysed and subjected to Western blot analysis to monitor the expression of Bcl-2, IAP family members, and cyclin D₁, as described in “Materials and methods.” For each condition, lanes were loaded with 30 μg protein; blots were subsequently reprobed for actin to ensure equivalent loading and transfer of protein. Results of a representative experiment are shown; 2 additional studies yielded equivalent results. CF indicates cleavage fragment.