Breast cancer stem cells (BCSCs) are identified as a small population of cells that have specific molecular signatures such as CD44+/CD24−, Aldehyde dehydrogenase 1 high (ALDH1high), and CD133+ (Al-Hajj et al., 2003; Al-Hajj and Clarke, 2004; Butti et al., 2019). The gene discussed is CD44; the disease is breast cancer.