Establishment of MDA-MB-231 and MCF-7 cell clones overexpressing CD44v8-10. The expression of panCD44 and CD44v9 was determined by western blot analysis (asterisk, CD44s; arrow, CD44v8-10). MCF-7 cells overexpressing CD44s were also established. WB, western blot; CD, cluster of differentiation; CD44v, variant isoform of CD44; EV, empty vector; Cl, clone; CD44s, standard isoform of CD44.