FLT1 and preeclampsia: Moreover, in vitro functional assays revealed that altered maternal serum proteome in the first trimester can affect the trophoblastic transcriptome and up-regulate FLT1. This is in agreement with reports indicating that maternal blood factors in preeclampsia can induce trophoblastic soluble endoglin overexpression and the development of preeclampsia-like symptoms in mice (85, 275).