CD44 and head and neck cancer: As such, a number of cell surface-specific antibodies were employed in various cell lines to optimise the identification of CTCs: breast cancer (anti-Trop2, -CD49f, -CD146, -CK8, -c-Met, -CD44, -CD47, -AQP5, -ADAM8, -TEM8) [81]; non-small cell lung cancer (ALDH1, EGFR, Met, HER3) [86]; head and neck cancer (cytokeratin, EGFR, vimentin, N-cadherin, CD44) [87].