Figure 2. Clinically pursued avenues to therapeutically interfere with vascular endothelial growth factor (VEGF)/VEGFR signalling. Production of VEGF in VEGF-producing cells can be blocked with VEGF ribozymes or VEGF siRNAs. VEGF protein can be neutralized with neutralizing antibodies (Avastin), soluble receptors (VEGF trap) or VEGF aptamers. Activation of the VEGF receptors can be effectively inhibited with specific small molecular weight tyrosine kinase inhibitors. Lastly, the synthesis of VEGF receptors can be blocked with VEGFR ribozymes or siRNAs.