CXCR4 and head and neck squamous cell carcinoma: Among them, cyclooxygenase 2 (COX2), the chemokine receptor CXCR4 and the matrix metalloproteinase 9 (MMP9) as well as apoptosis related genes are associated with the malignant phenotype of HNSCC and have been shown to be regulated by variable levels of nuclear receptor cofactors, albeit in other models [31–33].