Consistent with a pro-absorptive role for ClC-2, cAMP-stimulated Cl− secretion is increased in Clcn2−/− mice and early lethality of the Cftrtm1Eur mouse, that carries the CFTR-∆F08 CF mutant, is markedly ameliorated upon additional inactivation of Clcn2 [14]. This evidence concerns the gene CFTR and cystic fibrosis.