CFTR and cystic fibrosis: All designed analogs of Esc peptides showing a CFTR potentiator effect were also analyzed for their antibacterial activity by determining the corresponding minimal inhibitory concentration (MIC) towards Gram-negative bacterial strains and the Gram-positive bacterium Staphylococcus aureus (which is another relevant bacterial pathogen in CF [40]), in comparison to the Glu-containing analogs.