Optimizing nasal potential difference analysis for CFTR modulator development: assessment of ivacaftor in CF subjects with the G551D-CFTR mutation. oleh Steven M Rowe, Bo Liu, Aubrey Hill, Heather Hathorne, Morty Cohen, John R Beamer, Frank J Accurso, Qunming Dong, Claudia L Ordoñez, Anne J Stone, Eric R Olson, John P Clancy, VX06-770-101 Study Group