Inhibition of WNT1 changes the phenotype of CD44+CD24−ALDH1 stem cells and reduces their ability to form tumours and cell migration [13], and suppression of GSK3/β-catenin signals by an inhibitor of protein kinase D1 (PRKD1) is sufficient to reduce the stem and chemoresistance of breast cancer cells [14]. This evidence concerns the gene CD44 and breast cancer.