SLC12A2 and acute respiratory distress syndrome: Cl− enters in cotransport with Na+, and can leave the cell along an electrochemical gradient on the apical side through CFTR, resulting in Cl−-driven fluid secretion and subsequently alveolar liquid accumulation as seen in pulmonary edema and ARDS (Weidenfeld and Kuebler, 2017), and TNF alpha upregulates NKCC1 mRNA and protein levels.