Thus, the rapid increase in TGF-β2 expression that is observed following 4 days of TKI treatment persists after chronic adaptation to TKIs, indicating that the TGF-β pathway may play an important role in the response of HNSCC cells to inhibitors of dominant receptor tyrosine kinase (RTK) pathways. This evidence concerns the gene NTRK1 and head and neck squamous cell carcinoma.