CA9 and squamous cell carcinoma: Analysis of The Cancer Genome Atlas (TCGA) datasets first revealed that NSCLC patients with stage I–IV adenocarcinoma (LUAD; n = 507) and squamous cell carcinoma (LUSC; n = 502) had significantly higher expression of HIF1α, CA9 (CAIX), SLC16A3 (MCT4), SLC2A1 (glucose receptor-1; GLUT1), and pyruvate dehydrogenase kinase 1 (PDK1) in tumor tissues compared with adjacent normal tissues (p < 0.001; Figure 1A,B).