Approximately 70% of claudin-low breast cancers are TNBC, with high frequency of metaplastic and medullary breast carcinomas; these tumors are characterized by low levels of cell adhesion molecules and elevated expression of immune-related genes, such as CD4 and CD79a, and by mesenchymal features (high expression of CD44, vimentin, and N-cadherin) and low epithelial differentiation (low CD24 expression), resembling a mammary stem-like phenotype, which was acquired by EMT [112]. Here, CD24 is linked to breast cancer.