Ectopic overexpression of Smac/DIABLO enhanced Epo B– or Apo-2L/TRAIL–induced processing and activity of caspase-3 and down-regulation of the levels of XIAP, cIAP, and survivin.

Jurkat cells were transiently transfected with either the control vector (pcDNA Zeo) or pcDNA-expressing Smac (pcDNA Smac). Twenty-four hours after transfection, cells were treated with 10 nM Epo B (A) or 2.5 ng/mL Apo-2L/TRAIL (B) for 24 hours. Following this, cell lysates were obtained from treated and untreated cells, and immunoblot analysis of caspase-8 (processing), Bid, PARP, caspase-3, XIAP, cIAP1, or survivin was performed; β-actin was used as loading control.