CLEC4F and dry eye syndrome: In the present study, we used the Clec4f-cre system to delete Shp2/protein tyrosine phosphatase nonreceptor 11 (Ptpn11) in KCs,13 and combination of Clec4f-cre and adeno-associated virus (AAV)-cre to delete Shp2 in KCs and hepatocytes.