CXCR4 and head and neck squamous cell carcinoma: CXCR4 has been implicated in tumour metastasis in several tumour models including melanoma (Neagu et al., 2015), prostate (Lee et al., 2014) and neuroblastoma metastasis (Mühlethaler‐Mottet et al., 2015) and has been suggested as a biomarker for HNSCC with high metastatic potential (Albert et al., 2013).