CFTR and cystic fibrosis: Quantification of all isoforms of CFTR RNA (total CFTR), analyzed using primers to the common exons 11 to 14, revealed that ASO-23AB treatment resulted in a threefold increase in total CFTR mRNA compared to untreated samples, a level that is ∼30% of the CFTR mRNA quantity in WT non-CF donor hBE cells (Fig. 4 E and F).