Relative to other TNBC subtypes, claudin-low is characterized by a low expression of epithelial tight-junction claudin proteins, mucin 1 (MUC1), EPCAM and E-cadherin (CDH1), and high expression of epithelial-to-mesenchymal transition (EMT) markers, along with cancer stem cell (CSC) characteristics [5, 6]. Here, MUC1 is linked to cancer.