The table displays the total number of tumors formed, divided by the total number of injections performed. 100 - 25 000 cells of each group were injected subcutaneously into immunodeficient mice. Tumourigenicity was not determined (ND) for 25 000 Aldefluorhigh CD133high cells. TRA-1-85+ represent viable, single SW872 cells. The results are accumulated over three individual experiments.