Then, we examined the properties of CD24−/low/CD44+ cells related to tumor progression by comparing MDA-MB-231 cells and RT-R-MDA-MB-231 cells harboring different proportions of CD24−/low/CD44+ cells with the CD24−/low/CD44+ cells isolated from RT-R-MDA-MB-231 cells. The gene discussed is CD44; the disease is neoplasm.