Tumour growth is dependent on multiple factors, including the physiological process of angiogenesis. Several opportunities for inhibiting angiogenesis with targeted therapies have been identified and are currently being evaluated for clinical efficacy. Some of the most promising approaches include small-molecule inhibitors for the tyrosine receptor kinase VEGFR2. Other signal-transduction pathways have also been shown to regulate angiogenesis, including FGFR, PDGFR, Tie and EphB.