CFTR and malignant colon neoplasm: Interestingly, mutations in the Cl− channel Cystic Fibrosis Transmembrane conductance Regulator (CFTR), which is expressed in the luminal membrane of colonic crypt cells (Crawford et al., 1991), have also been suggested to be inversely associated with colon cancer (Padua et al., 1997), supporting the possibility for Cl−-dependent effects of SLC26A3.