Furthermore, the CFTR protein has been postulated to be important for P. aeruginosa internalization inside lung epithelial cells [25], which supports the idea that the clinical CF isolates PAET1, PAET2, and PAET4 may have undergone directed adaptation to allow them to colonize CFBE41o- cells, as we have detected in our work. Here, CFTR is linked to cystic fibrosis.