MME and invasive breast carcinoma: Normally in breast tissue, myoepithelial cells, lining the outer layer of the ducts, solely express CD10. However, in invasive breast carcinoma, there is an accumulation of CD10-cleaved peptides as the CD10 enzymatic activity is upregulated. These peptides inhibit epithelial cell differentiation, which promotes epithelial-mesenchymal transition and malignant proliferation [3,7].