The extracellular adherence protein (Eap), a broad-spectrum adhesin secreted by Staphylococcus aureus, was previously shown to curb acute inflammatory responses, presumably through its binding to endothelial cell (EC) ICAM-1. Examining the effect of Eap on endothelial function in more detail, we here show that, in addition, Eap functions as a potent angiostatic agent. Concomitant treatment of EC with purified Eap resulted in the complete blockage of the mitogenic and sprouting responses elicited by vascular endothelial growth factor (VEGF)₁₆₅ or basic fibroblast growth factor (bFGF). Moreover, the induction of tissue factor and decay-accelerating factor were repressed by Eap, as determined by qRT-polymerase chain reaction (qRT-PCR), with a corresponding reduction in Egr-1 protein up-regulation seen. This angiostatic activity was accompanied by a corresponding inhibition in ERK1/2 phosphorylation, while activation of p38 was not affected. Inhibition occurred downstream of tyrosine kinase receptor activation, as comparable effects were seen on TPA-induced ERK1/2 phosphorylation. Similar to previously described angiostatic agents like angiopoietin-1 or the 16-kDa prolactin fragment, Eap blockage of the Ras/Raf/MEK/ERK cascade was localized by pull-down assay at the level of Ras activation. Eap’s combined anti-inflammmatory and antiangiogenic properties render this bacterial protein not only an important virulence factor during S. aureus infection but open new perspectives for therapeutic applications in pathological neovascularization.--Sobke, A. C. S., Selimovic, D., Orlova, V., Hassan, M., Chavakis, T., Athanasopoulos, A. N., Schubert, U., Hussain, M., Thiel, G., Preissner, K. T., Herrmann, M. The extracellular adherence protein from Staphylococcus aureus abrogates angiogenic responses of endothelial cells by blocking Ras activation.