CD133 was expressed by a majority of tumor cells in the HCT116 cell line (68%), whereas in the remaining cell lines, it was expressed either by a moderate proportion of tumor cells [as in the Caco2 (49%) and HT29 (26%) lines] or by a restricted cell subset [as in the Lovo (4%) and SW620 (9%) cell lines]. The gene discussed is PROM1; the disease is neoplasm.