EPCAM and neoplasm: IF staining using a pan-cytokeratin antibody, as well as seven additional epithelial proteins including CK5, CK18, CK19, EpCAM, E-Cadherin, P-Cadherin, and p63, confirmed that residual HER2/neu tumor cells generally lacked expression of epithelial markers, suggesting that they had undergone an EMT (Additional file 8: Fig. S6).