Fig. 6. Specific ion conductance (G_m) of the wild-type and F508 mutant cystic fibrosis transmembrane-conductance regulator (CFTR) in forskolin-stimulated transfected mouse fibroblast cells. The untreated mutant cells have very low conductance compared with the wild type, while cells exposed to 300 mmol l^–1 of the indicated osmolytes had conductance rates as great or greater than the wild type (modified from Howard et al., 2003). *Significant difference compared to wild type.