FLT1 and lymphatic malformation: Comparing multiple samples of ten pooled fast-flow malformation patients (arteriovenous malformations = “Group 1”) to ten pooled slow-flow malformation (SF) patients (venous and lymphatic malformations = “Control Group”) an upregulation of VEGFA, VEGFB, VEGFC, VEGF-receptor 1 (VEGFR-1 = FLT1), VEGF-receptor 2 (VEGFR-2 = KDR) and the VEGF co-receptors Neuropilin-1 (NRP-1) and Neuropilin-2 (NRP-2) was detected in fast-flow malformations.