VX-770 is an orally bioavailable CFTR potentiator and VX-770 is in clinical development for the treatment of Cystic fibrosis. VX-770 bound directly to the CFTR protein, rather than associated kinases or phosphatases. VX-770 can cause CFTR channel opening through a non-conventional, ATP-independent mechanism. In recombinant cells VX-770 increased CFTR channel open probability (P(o)) in both the F508del processing mutation and the G551D gating mutation. VX-770 also increased Cl(-) secretion in cultured human CF bronchial epithelia (HBE) carrying the G551D gating mutation on one allele and the F508del processing mutation on the other allele by approximately 10-fold, to approximately 50% of that observed in HBE isolated from individuals without CF. VX-770 reduces excessive Na(+) and fluid absorption to prevent dehydration of the apical surface and increased cilia beating in these epithelial cultures.