Induction of apoptosis by scFvFITC:sTRAIL in RTX-FITC pretargeted CD20pos PR1 leukaemia cells was significantly inhibited in the presence of excess amounts of TRAIL-neutralizing mAb 2E5 (Fig. 1E), indicating that apoptotic activity was due to activation of TRAIL-R apoptotic signalling. The gene discussed is TNFSF10; the disease is leukemia.