AQP9 and head and neck squamous cell carcinoma: In the TCGA-HNSC cohort, we observed the expression of 12 ion channel genes in tumor and normal tissues; ANO1, AQP9, BEST2, CHRNA5, and KCNJ15 were upregulated in HNSCC, while AQP1, AQP5, SCNN1G, and SCN4A were downregulated (Figure 9A).