In particular, the first report on the use of PNAs as target site blockers in cystic fibrosis was published by Zarrilli et al., who tested the ability of PNAs fully complementary to the CFTR 3′UTR sequence recognized by miR-509-3p, in order to rescue the CFTR expression in the A549 cellular model co-transfected with a pLuc-CFTR-3′UTR vector [68]. The gene discussed is CFTR; the disease is cystic fibrosis.