ABCB5 and neoplasm: The phenomenon that transplantation of GEPhighABCB5+ cells resulted in a heterogeneous populations consisting of GEP and ABCB5 positive and negative cells suggested that tumor hierarchy existed, in which the GEP+ and ABCB5+ cells were able to self-renew and differentiate, generating their positive and negative counterparts in the tumor mass (Figure S5).