FOXI1 and cystic fibrosis: Similar to human cystic fibrosis cultures12, FOXI1-KO ALI cultures demonstrated a 2.3-fold (P < 0.0092) slower fluid absorption rate (Fig. 1d) and 40% reduction (P < 0.0001) in ASL height at 24 h of equilibration, compared with wild-type cultures (Fig. 1e and Extended Data Fig. 2e).