CXCL1 and Respiratory insufficiency: As an inflammatory cell infiltrate was observed in both the lungs of 8–16-week-old Muc5bko/+ mice (data not shown) and in older mice with lung disease, we assessed the levels of the pro-inflammatory chemoattractant chemokine CXCL1/KC in bronchoalveolar lavage (BAL) of adult WT and Muc5bko/+ mice, which displayed no signs of respiratory insufficiency.