TNFSF10 and colorectal cancer: Importantly, the PARP cleavage observed in RKO and HCT116 tumor cells was not observed in non-transformed CO841 colon epithelial cells, suggesting that the non-tumorigenic cells have a mechanism of resistance to TRAIL that is likely to be different from the TRAIL-resistant colorectal cancer cell lines (Fig. 3C and Supplementary Fig. 4).