NEDD4 and dry eye syndrome: Expression of genes associated with endocytic function, cytoskeleton organization, and positive regulators of endocytosis, such as 1-phosphatidylinositol-4-phosphate 5-kinase (Pip5klc), phospholipase D1/2 (Pld2), integrin subunit beta1 (Itgb1), GTPase Hras, clathrin adaptor protein (Dab2), caveolin1 (Cav1), and E3 ligase NEDD4 (Nedd4) were higher in LSECs than in KCs (Additional file 2).