The proteasome inhibitor, bortezomib, has been demonstrated to sensitize tumor cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. Natural killer (NK) cells represent potent antitumor effector cells. They also express TRAIL. Therefore, we investigated whether bortezomib could sensitize tumor cells to NK cell-mediated killing, and have the same effect in ...