To investigate whether enhancement of bacterial proliferation in CF airways was related to a defect in the antimicrobial peptides hBD1, hBD2 and LL-37, we first measured their expression (mRNA) and showed no difference in either CFBE41o− cells or primary cells independently of the genotype (WT or F508del) (Supplemental Fig. 13). The gene discussed is DEFB1; the disease is cystic fibrosis.