CD44 and neoplasm: It was suggested that this intratumor heterogeneity is perpetuated by tumor stem-like cells, leading many research groups to focus on the identification of biomarkers that allow them to target those cells responsible for tumor maintenance, including CD44 [5], CD29 and CD49f, [6], CD133 [7], Lgr5 [8], Procr [9], ALDH [10], or CD61 [11].