MUC1 and breast cancer: In BC, MUC-1 (CD227) overexpression has been correlated with cell adhesion inhibition and increased metastatic potential of tumor cells [14–17] while syndecan-1 (CD138), a transmembrane receptor involved in cell-cell adhesion, cell mobility, proliferation and differentiation, has been related to an aggressive phenotype and poor clinical behavior [18–20].