TMPRSS2 and cystic fibrosis: Furthermore, in a recent analysis, increased angiotensin-converting enzyme-2 (ACE2) mRNA, and decreased transmembrane protease serine 2 (TMPRSS2) mRNA, were described in CF airway epithelial cells when compared to non-CF cells [72,75,76], both of which are important proteins for the SARS-CoV-2 entry in cells.