For instance, in breast cancer, markers such as CD44high/EpCAMhigh, CD44+CD24−/low, CD49f+/EpCAM+, and CD49f high/CD61high, as well as the combination of CD44+CD24−/low and ALDH+, are employed to identify and isolate breast CSCs (32, 33) Additionally, the cell surface marker ABCG2, a member of the ATP-binding cassette superfamily G, can be utilized to select for CSCs (34). This evidence concerns the gene CD44 and breast cancer.