FLT1 and preeclampsia: Recently, circulating antiangiogenic proteins, soluble vascular endothelial growth factor receptor 1 [VEGF-R1, also referred to as soluble fms-like tyrosine kinase (sFlt1)] and soluble TGF-β co-receptor endoglin (sEng), have been implicated in the pathogenesis of many of the maternal features of preeclampsia.