EGFR and head and neck squamous cell carcinoma: Since several ErbB family members, including HER1 (EGFR), HER2 and HER3, seem to be strong predictors for the outcome of HNSCC (67), we stained different tumor samples post-surgery from corresponding relapsed patients for HER1/2 and collected PB for NK cell separation as well as blood plasma for quantification of sMICA and TGF-β1.