This resilience was confirmed in 2008 by Fillmore et al. [54] who used a chemotherapeutic approach on a larger number of breast cancer cell lines, but who also performed xenotransplantation assays comparing unsorted and CD44+ve/CD24−ve/ESA+ve sorted cells and observed a much greater tumour initiating capacity in the sorted subpopulation. The gene discussed is CD44; the disease is breast carcinoma.