NTRK1 and head and neck squamous cell carcinoma: Using RNA isolation, reverse transcription, PCR and in situ hybridization (ISH), the mRNA expression of NGF, and using immunohistochemistry (IHC), the protein synthesis of NGF receptors, NTRK1 and p75NTR, were investigated in normal mucosa from uvulopalatopharyngoplasties (UPPP) in HNSCC tumor tissue and in HNSCC cell lines.