CD44 and neoplasm: Next, the biological behaviors of the newly converted CD44+/CD24- CSCs from CD44-/CD24- MDA-MB-231 cells (CD44-/CD24- CSCs) and parental CSCs directly purified from MDA-MB-231 cells (WT CSCs) were measured for their mammosphere formation, self-renewal, tumor cell differentiation, and CSC stemness marker expression in vitro and their tumorigenicity in vivo.