Growth factor active in angiogenesis and endothelial cell growth, stimulating their proliferation and migration. It binds to the receptor FLT1/VEGFR-1. Isoform PlGF-2 binds NRP1/neuropilin-1 and NRP2/neuropilin-2 in a heparin-dependent manner. Also promotes cell tumor growth. Antiparallel homodimer; disulfide-linked. Also found as heterodimer with VEGFA/VEGF. Isoform PlGF-3 is found both as homodimer and as monomer. The three isoforms are secreted but PlGF-2 appears to remain cell attached unless released by heparin. While the three isoforms are present in most placental tissues, PlGF-2 is specific to early (8 week) placenta and only PlGF-1 is found in the colon and mammary carcinomas. Isoform PlGF-2 contains a basic insert which acts as a cell retention signal. N-glycosylated. Belongs to the PDGF/VEGF growth factor family. Wrong choice of frame.