PROM1 and malignant colon neoplasm: In this tumour, a CD133+ subpopulation of colon cancer cells was recently demonstrated to be highly enriched in tumour-initiating colon CSCs (Co-CSCs) that have the ability to self-renew and to recapitulate the bulk tumour population (O'Brien et al, 2007; Ricci-Vitiani et al, 2007).