The results of our analyses of CD133 expression in colon cancer are somewhat higher than that reported previously (1.8–25% O’Brien et al, 2007; Ricci-Vitiani et al, 2007) and more in accordance with those more recently reported by Shmelkov et al (2008) in primary human colon tumours. The gene discussed is PROM1; the disease is malignant colon neoplasm.