KLK4 and cystic fibrosis: Moreover, a number of previous results about CF-specific abundance of proteins were confirmed: (i) the decreased levels of kallikreins were already described in sweat [26] and correlated with a decreased enzymatic activity in CF plasma [27], (ii) the decreased arginase-1 abundance in CF sweat would correlate with the decreased abundance and reduced enzymatic activity in CF plasma [28], (iii) the under-expression of filamins A and B in CF sweat could be correlated with the decreased cell levels of filamins [29].