CD44+/CD24-/low stem cell/progenitor cells were isolated from normal and immortalised mammary cells (HMEC and MCF10A, respectively), LUM (MCF-7, HCC1428), HER2-E (MDA-MB-468, HCC1954) and TN (BT549, Hs578T and MDA-MB-231) cancer cells. This evidence concerns the gene CD44 and cancer.