For example, we combined the expression of CD44 (cluster of differentiation gene 44), ITGA6 (integrin subunit alpha 6), DNER (delta/notch like EGF repeat containing), ALDH1A3 (aldehyde dehydrogenase 1 family member A3), and ABCG2 (ATP binding cassette subfamily G member 2) to characterize breast cancer stemness. This evidence concerns the gene CD44 and breast cancer.