Of particular interest in CF, electrophysiologic assays have demonstrated the presence of functional CFTR in HNE cultures, and paired samples of brushed HNE and brushed HBE from the same patient (among a cohort of patients with CF) have shown similar CFTR dependent ion transport and a strong correlation in the ability to detect CFTR response to modulation between the two culture types [31]. This evidence concerns the gene CFTR and cystic fibrosis.