Endothelial cells, which line the innermost layer of blood and lymphatic vessels, are key regulators of the vascular tone, immune response, inflammation, barrier function and angiogenesis. The proper control of these functions is essential to maintain tissue homeostasis, vascular integrity and the overall physiological function. Endothelial cell–cell junctions are involved in control of vascular permeability and leucocyte extravasation. Besides these, junctional complexes regulate several cellular processes such as proliferation, survival and the activity of growth factor receptors. The activation of the vascular endothelial growth factor receptors (VEGFRs) triggers angiogenesis, characterized by cell growth, survival, migration and increased vascular permeability. The dysfunction of this signalling pathway is implicated in the pathogenesis of cancer, being tumour angiogenesis a critical step in cancer progression and metastasis. Blocking angiogenesis by targeting VEGF and VEGFRs is considered important for the development of anti-cancer therapies.