CD44+/CD24− has been widely used as BCSC surface markers, thus we sorted CD44+/CD24− subpopulation (termed as BCSCs) from various breast cancer cells and clinical tumor samples, and other remaining subpopulations (CD44+/CD24+, CD44−/CD24+, CD44−/CD24−) were termed as non-BCSCs. Here, CD44 is linked to breast cancer.