CLDN3 and cholangiocarcinoma: Human bile contains inorganic electrolytes, lipids (bile acids, phospholipids, and cholesterol), bilirubin, and proteins, and is abundant in EVs that can be isolated and characterized using standard protocols, typically yielding vesicles of ~30–200 nm in size [81,82].Bile-derived EVs have been reported to contain higher amounts of Claudin 3 protein in Cholangiocarcinoma (CCA) cohorts compared to biliary stone disease patients, showing potential as a diagnostic marker for CCA [83].