Usp24 KD reduces Mcl-1 levels and myeloma cell survival. (A) Usp24 or Mcl-1 were knocked down by control or specific shRNA retrovirus and selected for puromycin resistance before cell lysates were examined for the protein indicated (left) or cell survival by measurement of annexin positivity (right). The results represent the average ± SD of triplicate assays. (B) RPMI-8226 myeloma cell lines were subjected to siRNA-mediated KD of control (luciferase), Usp9x, or Usp24 before assessing the protein indicated by immunoblotting (left). Increase in annexin positivity was assessed as a measure of cell viability. The values represent the average ± SD of 3 replicates from 2 independent experiments. **P < .01; ***P < .005.