Dallas et al (21) demonstrated that compared with their parental cells, 5-Fu-resistant colon cancer cells (HT29/5Fu-R) highly expressed the stem cell phenotype (CD133+/CD44+), indicating that a 5-Fu insensitive subpopulation of cancer stem cells is the source of resistance to chemotherapy. The gene discussed is PROM1; the disease is malignant colon neoplasm.