CFTR and cystic fibrosis: Similar to non‐CF observations, CFTR‐mediated changes in PD and IT elicited by post‐amiloride exposure to F/I, VX‐770, and CFTR(inh)‐172 were increased in the presence of a chloride gradient for epithelia from CF individuals with the genotype F508del/F508del (Figure 2a–c).