Basic fibroblast growth factor (bFGF) has been shown to initiate signalling pathways important for cell proliferation and cell survival, both key steps in angiogenesis. The Src homology-2 domain containing tyrosine phosphatase (Shp-2) can be activated by bFGF, but its role in bFGF-dependent signalling is unknown. Using antisense oligonucleotide (AS ODN) magnetofection, a technique where AS ODNs coupled to nanoparticles are rapidly delivered to cells under influence of an external magnetic field, we investigated the role of Shp-2 in cell proliferation and survival. All experiments were performed with human microvascular- and umbilical vein endothelial cells (HMEC, HUVEC). Data are presented as means ± S.E.M. Student’s t test was used for analysis. Results were considered significant when p<0,05. AS-ODN magnetofection against Shp-2 led to a knock-down of Shp-2 protein (0.5μg AS-ODN/ml)in HUVECs and HMECs as assessed by Western blotting. Basal proliferation of HMECs, as measured by MTT reduction, was significantly inhibited up to 41% in Shp-2 AS ODN-treated cells as compared to nonsense oligonucleotides (NS ODN)-treated cells (± 5% p<0.05, n=12). In addition, bFGF (10ng/ml)-dependent proliferation following Shp-2 knock down was impeded to a similar extent (by 57 ± 13 %; p<0.05, n=12). To investigate if this decrease was due to an enhanced apoptosis, cell cycle analysis by flow cytometric propidium iodide and subsequent Annexin V staining were performed. This revealed a 1.4-fold increase in cells detected in the subG0 fraction (± 0.5; p<0.05, n=6) and a significant rise in Annexin V-positive cells (n=9) following Shp-2 AS ODN transfection, in contrast to NS ODN-treated cells. This increase of apoptosis was associated with a decreased phosphorylation of the PI3-kinase regulatory subunit p85 (24 ± 6%, p<0.05, n=3) and its downstream target Akt (n=4). A diminished phosphorylation of the MAP kinase ERK 42/44 was also observed despite bFGF stimulation (n=4). Our results indicate that Shp-2 protects human endothelial cells from apoptosis, possibly by enabling bFGF-dependent activation of PI3-K and/or MAP kinase. Inhibition of Shp-2 increases apoptosis rates of endothelial cells which leads to an inhibition of basal and prevention of bFGF-dependent proliferation.