AQP3 and cancer: In particular, AQP1, AQP3 and AQP5, in addition to their physiological role in transepithelial water transport, skin hydration and fluid secretion [1,19,24,25], were found to be overexpressed in several types of cancer [26,27,28,29], such as colon cancer [30], hepatocellular carcinoma [31] and pancreatic ductal adenocarcinoma [32], being correlated with tumor progression, metastasis and poor patient prognosis, and implying their importance as prognostic markers and therapeutic targets for anticancer drug discovery.