KDR and neoplasm: The expression of αvβ3 is up-regulated in tumour associated blood vessels32 and drugs targeting αvβ3 have shown some success in clinical trials (rev in33); however its role appears quite complex, since deficiency of this integrin in the mouse has been linked with increased VEGFR2-dependent angiogenesis.34 Interestingly αvβ3 can associate with VEGFR2 and crosstalk between these receptors can stimulate reciprocal activation (rev in35).