The effects of 24 h-treatment with lumacaftor were assessed here by determining CFTR-mediated Cl− secretion in HBE cells from CF donors with the following genotypes (Fig. 1): wt/wt control (a, b); F508del/F508del-Donor 1 (c, d); F508del/F508del-Donor 2 (e, f); A561E/A561E (Fig. 1g, h) and also on the additional genotypes (Fig. 2): N1303K/G542X (a, b), F508del/G542X (c, d); F508del/Y1092X (e, f). The gene discussed is CFTR; the disease is cystic fibrosis.