CD44 and breast cancer: CSC markers include CD44+/CD24-/low in breast cancer (Al-Hajj et al., 2003), CD133+ in brain tumors (Singh et al., 2004) and CRC (Ricci-Vitiani et al., 2007), ALDH high in thyroid cancer (Todaro et al., 2010), CD44+/α2β1high/CD133+ in prostate cancer, and numerous markers in other solid tumors (Medema, 2013).