Ang2 is a growth factor ligand of the Tie family of protein receptor tyrosine kinases.33 Ang2 promotes the dissociation of pericytes and loosens the cellular junctions, which results in unstable blood vessels.34 Increasing levels of circulating Ang2 in this setting would appear to be indicative of effective tumour destabilisation. This evidence concerns the gene TIE1 and neoplasm.