Figure 1c,d shows concentration–response relationships for lumacaftor‐rescued F508del‐CFTR and G551D‐CFTR in FRT epithelia potentiated by CP‐628006 and ivacaftor, while Figure 1e,f shows equivalent data for epithelia of human bronchial epithelial cells from cystic fibrosis patients (genotypes: F508del/F508del and F508del/G551D). The gene discussed is CFTR; the disease is cystic fibrosis.