NTRK2 and head and neck squamous cell carcinoma: Brain-derived neurotrophic factor gene expression was detected in both SCC-25 and UPCI-SCC090 HNSCC cell lines (Figure 3A), NTRK2 was high expressed in UPCI-SCC090 cells (Figure 3A,B,E), and low expressed in SCC-25 cells (Figure 3A,B,D).