PGF and preeclampsia: Thus, sEng levels in plasma, as well as the ratio between plasma levels of soluble fms-like kinase 1 (sFlt1), a soluble form of the vascular endothelial growth factor (VEGF) receptor type-1, and placental growth factor (PlGF, a member of the VEGF family) are increased weeks before the onset of preeclampsia [17,31,32].