Ke et al. reported that miR-221 was highly expressed in basal (SUM149, HCC1954) and claudin-low (SUM159, SUM1315, MDA-MB-231) breast cancer cells, as well as ALDH1+ or CD44+/CD24− BCSCs derived from luminal (MCF-7) and basal (HCC1954) cell lines [60]. The gene discussed is CD44; the disease is breast cancer.