CD44 and breast cancer: Analysis of different molecular subtypes of breast cancers indicated that the metastatic rates in the patients with a high frequency of CD44-/CD24- breast cancer cells were significantly higher than those with a low frequency of this type of cells (i.e. 40.85% vs. 6.82% for luminal; 47.06% vs. 13.64% for HER-2+; 63.79% vs. 22.22% for TNBC with a high vs. low frequency of CD44-/CD24- tumor cells; Figure 1C).