NTRK1 and neoplasm: Moreover, endothelial cells are known to express receptor tyrosine kinases vascular endothelial growth factors (VEGFR) and platelet-derived growth factors (PDGFR), in which binding of VEGF or PDGF to VEGFR and PDGFR on endothelial cells elicits endothelial cells proliferation, migration and tumour neovascularization [25].