Pairwise CLDN biomarker AUC comparisons (heatmap, Figure 2, right panel), across 12 tumor types (The Cancer Genome Atlas; TCGA data), showed that CLDN1 could readily distinguish colon from kidney, brain, lung, and ovary cancers, while both CLDN1 and CLDN4 (but not CLDN18) could distinguish brain from kidney cancer. This evidence concerns the gene CLDN4 and cancer.