ABCG2 and breast neoplasm: For this purpose, we purified bCSCs flow-cytometrically from primary breast tumors on the basis of the cell surface phenotype CD44+/CD24-/low (Figure 8A) and confirmed their stemness properties on the basis of the expression levels of the following markers: MRP1 and ABCG2 (Figure 8B), ALDH1 (Figure 8C), and Oct-4, Sox-2, and Nanog (Figure 8D).