CFTR and cystic fibrosis: In this study, we aimed to (a) directly compare electrophysiological characteristics in 2D HIO to HNE, (b) validate drug responsiveness of CFTR in 2D HIO against the current standard methods of HNE and 3D HIO, (c) evaluate clinical predictability of the in vitro CFTR drug responses measured in 2D HIO, and (d) assess feasibility of studying other apical membrane components relevant in CF.