TNFSF10 and cancer: Since our ELISA experiments did not detect TRAIL either as a soluble protein or bound to vesicles upon the IFNα stimulation of the epithelial cancer cells analyzed and since the supernatant of A549 cells failed to induce the cell death of sensitized target cells (Figure 4C), we conclude that TRAIL is not secreted in any form by the cancer cells analyzed in our study.