NTRK1 and cancer: Anti-angiogenics currently used in cancer therapy target angiogenesis by two major mechanisms: (i) neutralizing angiogenic factors or their receptors by using macromolecule anti-angiogenic drugs (e.g., therapeutic antibodies), and (ii) blocking intracellularly the activity of receptor tyrosine kinases with small molecule (Mr < 1 kDa) inhibitors.