One study demonstrated TRAIL-induced apoptosis of CD133-positive glioma cells (Sasportas et al, 2009), a second showed radioresistant oesophageal cancer cells were 10 times more susceptible to TRAIL therapy (Zhang et al, 2008) and a further study noted an increased sensitivity of colon cancer SP cells to recombinant TRAIL therapy (Sussman et al, 2007). This evidence concerns the gene PROM1 and central nervous system cancer.