Aims: Hypoxia/reoxygenation (H/R) triggers the release of the potent angiogenic stimulus vascular endothelial growth factor (VEGF) and of reactive oxygen species (ROS). The tyrosine phosphatase SHP-2 is activated by growth factors (GF), but it is unknown whether it is involved in H/R dependent angiogenesis and ROS generation. We investigated whether SHP-2 has a role in VEGF dependent ROS production and angiogenesis signalling in human endothelial cells (EC). Methods: SHP-2 activity in human microvascular endothelial cells (HMEC) was inhibited by SHP-2 siRNA magnetofection or application of the pharmacological inhibitor PtpI IV. SHP-2 activity was measured by the ability to dephosphorylate pNPP, its membrane recruitment was detected by cell fractioning and immunoblotting of the different fractions. Tyrosine phosphorylation of SHP-2 and Akt activation was assessed by Western blotting. Expression of VEGFRs was measured by FACS. Super oxide formation was determined by measuring cytochrome c reduction Results: One hour of hypoxia followed by one hour of reoxygenation (p<0.05, n=6) was associated with enhanced SHP-2 activity (p<0.05, n=7) and ROS production in HMEC. VEGF (50ng/ml, 10min) enhanced SHP-2 phosphatase activity (p<0.05, n=11) as well as membrane translocation (p<0.05, n=4) and phosphorylation of its tyrosine residues (p<0.05, n=3). Knock-down of SHP-2 by siRNA (50nM) prohibited VEGF dependent Akt activation (n=3) and inhibition of SHP-2 by PtpI IV application (2mM) impaired VEGF dependent formation of capillary like structures by 82±5% (p<0.01, n=2). As shown by western blotting and FACS both VEGFR-1 and -2 were naturally expressed on HMEC (p<0.001, n=3). Interestingly, SHP-2 did not bind to the VEGFR-2 upon VEGF stimulation (n=3) but SHP-2 siRNA significantly reduced the expression of VEGFR-2 at the cell surface (p<0.01, n=6). Conclusions: Our results indicate that SHP-2 is an essential signalling intermediate for VEGF dependent EC signalling and tube formation via regulation of Akt activity and VEGFR-2 expression.