Typically, BC stem cells (BCSCs) are identified and isolated by fluorescence-activated cell sorting (FACS); the most common isolation strategies for human BC cells are the antibody staining of the cell surface markers CD24 and CD44, and the evaluation of aldehyde dehydrogenase (ALDH) activity [7], with both the Lin−CD24−/lowCD44+/high and the ALDHhigh populations in breast tumors being enriched for CSCs. The gene discussed is CD44; the disease is breast cancer.