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VEGF Receptor 2 （VEGFR-2）, also known as KDR in humans and Flk-1 in mice, is a crucial receptor tyrosine kinase that plays a central role in angiogenesis, the formation of new blood vessels. This receptor has high affinity for VEGF-A and mediates most of the endothelial growth, migration, and survival signals induced by VEGF-A. Structurally, VEGFR-2 is a glycosylated transmembrane protein with a molecular weight of about 230 kDa, consisting of an extracellular domain （ECD） for ligand binding, a transmembrane domain （TMD）, a juxtamembrane domain （JMD）, a tyrosine kinase domain （TKD）, and a C-terminal domain （CTD） for signaling. Upon binding to VEGF-A, VEGFR-2 undergoes dimerization and autophosphorylation, activating downstream signaling pathways such as the PLCγ-PKC-MAPK pathway, which promotes endothelial cell proliferation, migration, and vascular permeability. VEGFR-2 is widely expressed in vascular endothelial cells and is also found in some tumor cells, making it a key target for both pro-angiogenic therapies in conditions like ischemic diseases and anti-angiogenic therapies in cancer.