KDR has also been designated as VEFR-2 (Vascular endothelial growth factor receptor 2), CD309 (cluster of differentiation 309) and Flk1 (fetal liver kinase 1). Vascular endothelial growth factor (VEGF) is a major growth factor for endothelial cells. KDR is one of the two receptors of the VEGF. This receptor, known as kinase insert domain receptor, is a type III receptor tyrosine kinase. It functions as the main mediator of VEGF-induced endothelial proliferation, survival, migration, tubular morphogenesis and sprouting. The signalling and trafficking of this receptor are regulated by multiple factors, including Rab GTPase, P2Y purine nucleotide receptor, integrin alphaVbeta3, T-cell protein tyrosine phosphatase, etc.. Mutations of this gene are implicated in infantile capillary hemangiomas.