STAT3 and head and neck squamous cell carcinoma: Figure 1C demonstrated that all the tested HNSCC cell lines show constitutive STAT3 phosphorylation. Interestingly, BT inhibited STAT3 (Tyr705) activation only in UD SCC2, JMAR, YD-10B cells, and the levels of total STAT3 protein content were not affected (Figure 1C).