TNFSF10 and cancer: The main reasons for this are the intrinsic tumour-selective activity of TRAIL in a broad range of cancer cells that complements the rather nonselective delivery of viral vectors to tumours and normal tissues, the observed bystander effect of TRAIL resulting in the killing of cells surrounding the infected cells (Kagawa et al, 2001), and the notion that virally produced TRAIL may overcome problems observed with the use of recombinant soluble TRAIL regarding protein instability and resistance (Kelley et al, 2001; Voelkel-Johnson et al, 2002; Seol et al, 2003).