More recently, it has been shown that an active β1 integrin is trapped in the luminal pole of bronchial and nasal epithelial cells of CF individuals in vivo and in vitro, leading to the downregulation of the expression of acid ceramidase in human CF airway epithelial cells and thereby mediating a further accumulation of ceramide and a concomitant depletion of sphingosine [211]. The gene discussed is ASAH1; the disease is cystic fibrosis.