PGF and neoplasm: Here, we describe the potent anti-angiogenic, anti-tumor, and anti-metastatic activity of a tetrameric tripeptide named iVR1 (inhibitor of VEGFR1), which is able to specifically bind mouse and human VEGFR1 blocking receptor activation by preventing the interaction of the natural ligands VEGF-A, VEGF-B, PlGF and VEGF-A/PlGF heterodimer (IC50 6–10 μM) [28].