CFTR and cystic fibrosis: CFTR activation: via a cAMP/PKA‐dependent pathway: in the presence of 10 μM forskolin, which maximally activated the cAMP‐dependent CFTR chloride channel, the addition of nobiletin (100 μM) to the apical or basolateral membrane of 16HBE14o‐ human bronchial epithelial cells increased ISC by 12.03 ± 1.18 and 9.69 ± 1.38 μA cm−2, respectively. Confirming that the nobiletin‐stimulated Cl− secretion is due to the activation of CFTR, the CF cell line (CFBE41o‐), which lacks functional CFTR, no increase in ISC is observed after application of apical nobiletin (100 μM).