CD44 and breast cancer: At present, it is considered to belong to the claudin-low molecular subtype because the line displays a down-regulation of claudin-3 and claudinin-4, as well as low expression of the Ki-67 proliferative marker and an enrichment of markers associated with an epithelial-mesenchymal transition and an expression of traits associated with breast cancer stem cells (CSC), such as CD44+/CD24−/low phenotype.