Genes different between cancer stem cell populations in A1.8 and RP.1 cells included KRT15, a marker of basal breast cancer type [26], with 17-fold higher expression in RP.1 CD133+, and Desert hedgehog, with 4.3-fold higher expression in the A1.8 SC+ than in the SC- population. The gene discussed is PROM1; the disease is breast cancer.