Figure 2 : Vascular endothelial growth factor receptor (VEGF-R). signaling. VEGF-R can form homo- or heterodimeric complexes that are capable of binding different activating ligands. VEGF-A is the dominant ligand involved in signaling through VEGF-R2 to mediate new blood vessel formation in tumors. The activation of this receptor can be inhibited by binding of the ligand by an anti-VEGF-A antibody (bevacizumab) or by a small molecule VEGF-R tyrosine kinase inhibitors (VEGF-R TKi).