STAT1 and head and neck squamous cell carcinoma: In addition, the surface IFNAR1 was also widely expressed on CD4+ T, CD8+ T and CD56+ NK cells (Fig. 4k, Supplementary Fig. S10), and there was a positive correlation between STAT1 and PDCD1 mRNA encoding PD1 protein in HNSCC (Supplementary Fig. S11).