CFTR and chronic obstructive pulmonary disease: The introduction of both cAMP-dependent CFTR modulator (PDE inhibitor: roflumilast) and cAMP-independent CFTR modulator (CFTR potentiator: ivacaftor) has shown promise in potentiating CFTR function with increased CFTR-mediated Cl− ion transportation in the treatment of acquired CFTR dysfunction in COPD.