\textit{In vivo }Studies of VEGFR2 Interactions in the Presence and Absence of VEGF

Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) is a receptor tyrosine kinase (RTK) that is critical for vasculogenesis and angiogenesis.~ Enhanced VEGFR2 signaling is often correlated with malignancy.~ ~Recently, it was shown that full-length VEGFR2 exists in a monomer-dimer equilibrium in the absence of bound VEGF.~~ Thus, the canonical model of RTK activation does not seem to adequately describe the behavior of VEGFR2 in the cell membrane.~ In order to understand the role that VEGFR2 extracellular domain plays in unliganded dimerization in live cells, we utilize \textbf{F}ully Quantified \textbf{S}pectral \textbf{I}maging (FSI) to probe the interactions of VEGFR2 mutant constructs with rationally truncated EC domains.~~ In addition, we investigate the stoichiometry of ligand binding to VEGFR2 EC domain as a function of~ VEGF concentration and total receptor expression.~