Of the few studies that have addressed the sensitivity of cancer stem cells to TRAIL [16], the majority, including medulloblastoma [56], glioblastoma [19] and lymphoma [57]-derived stem cells, are resistant, with the exception of colorectal cancer cell lines in which a FACS sorted side-population was shown to be TRAIL responsive [58]. This evidence concerns the gene TNFSF10 and colorectal cancer.