Cancer cells are much more susceptible than normal cells to the cell-death-inducing effects of a protein known as TRAIL, a difference that may aid researchers who want to develop new cancer therapies. The reason for the difference has been unclear, but three groups, two of them writing on pages 815 and 818 of this issue, have now solved the puzzle: Normal cells, but apparently not cancer cells, produce a "decoy receptor" that binds TRAIL, but is incapable of transmitting its death message to the cell interior.