CD44 and breast cancer: Furthermore, studies have indicated that human breast cancers and cell lines contain a sub-population of cells characterised by CD44+/CD24−/low/Lin− cell surface markers, and a partial overlap between CD44+/CD24−/low/Lin− and ALDH1-positive populations was reported (Al-Hajj et al, 2003; Ginestier et al, 2007; Fillmore and Kuperwasser, 2008).