TNFSF10 and cancer: Both soluble and full-length TRAIL bind to their cognate cell surface receptors in the target cell to engage the apoptotic pathway (Ashkinazi et al, 1999) although the two TRAIL variants have been reported to possess different apoptosis-inducing capacities in cancer cells suggesting currently unresolved differences in their mechanism of action (Voelkel-Johnson et al, 2002; Seol et al, 2003).