Furthermore, for TCGA tumors with the data of the GTEx database as controls, CLDN6 expression was significantly upregulated in 20 cancer types, including ACC, BLCA, BRCA, CHOL, COAD, ESCA, HNSC, liver hepatocellular carcinoma (LIHC), LUAD, lung squamous cell carcinoma (LUSC), OV, pancreatic adenocarcinoma (PAAD), pheochromocytoma and paraganglioma (PCPG), rectum adenocarcinoma (READ), STAD, TGCT, thyroid carcinoma (THCA), thymoma (THYM), UCEC, and UCS, while it was downregulated in glioblastoma multiforme (GBM), KICH, KIRC, LAML, and brain lower grade glioma (LGG) (Figure 1D). This evidence concerns the gene CLDN6 and pheochromocytoma-paraganglioma.