CLDN12 and cholangiocarcinoma: Immunohistochemistry (IHC) of tumor samples and normal tissues from the Human Protein Atlas (HPA) database revealed that CLDN12 protein was highly expressed in LUSC, PRAD, COAD, READ, LIHC, cholangiocarcinoma (CHOL), breast invasive carcinoma (BRCA), and BLCA tumor tissues (Figure S5).