EPCAM and neoplasm: For example, tumor cells down-modulate the epithelial markers undergoing epithelial mesenchymal transition (EMT); thus, CellSearch fails to capture these EpCAM-negative CTCs, while the OBP-401 assay for CTC identification, which is based on the telomerase expression, -could be more suitable for the detection of tumor cells involved in EMT process [46].