CD44 and breast cancer: CSCs have been associated with normal stem cell‐like characteristics, including self‐renewal, differentiation, enhanced proliferative and invasive properties, chemoradiation resistance, high tumorigenic feature, and so on.7 A population of CD44+/CD24−/low cells has been demonstrated to have tumor‐initiating properties in breast cancer in 2003.8 The accumulating evidences suggested that breast cancers were initiated and maintained by a part of tumor cells with stem cell properties.