tokens: Nuclear factor ( NF ) -kappaB inhibitors , such as SN50 ( a cell-permeable inhibitor of the nuclear translocation and transcriptional activity of NF-kappaB ) or the proteasome inhibitor PS-341 , enhanced the proapoptotic activity of TRAIL/Apo2L against TRAIL-sensitive MM cells , whereas SN50 reversed the TRAIL resistance of ARH-77 and IM-9 MM cells .