Unlike these cation channels, the Cl− channel CFTR (cystic fibrosis transmembrane conductance regulator) and the Ca2+-activated Cl− channel regulators CLCA2 [28,29] and CLCA4 [30] (chloride channel accessory protein-2, -4 [31,32]) suppress EMT in breast cancer cells possibly by counteracting oncogenic alkalinization of intacellular pH. Here, CLCA4 is linked to breast cancer.