In a variety of cell types, the transcription factor nuclear factor B (NF-B) functions as a mediator of stress and immune responses. In endothelial cells (ECs), it controls the expression of genes encoding, eg, cytokines, cell adhesion molecules, and procoagulatory proteins. This study investigates the effect of NF-B suppression on several pathophysiologic functions of ECs, including inflammation, coagulation, and angiogenesis. A recombinant adenovirus was generated for expression of a dominant negative (dn) mutant of IB kinase 2 (IKK2), a kinase that acts as an upstream activator of NF-B. dnIKK2 inhibited NF-B, resulting in strongly reduced nuclear translocation and DNA binding activity of the transcription factor and lack of expression of several proinflammatory markers, including E-selectin, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, and interleukin-8. Concomitantly, inhibition of leukocyte binding to dnIKK2-expressing ECs could be demonstrated in a cell adhesion assay. Furthermore, expression of tissue factor as well as the ability to form capillary tubes in a matrigel assay was impaired in dnIKK2-expressing ECs. These data demonstrate that NF-B is of central importance not only for the inflammatory response but also for a number of other EC functions. Therefore, this transcription factor as well as its upstream regulatory signaling molecules may represent favorable targets for therapeutic interference. IntroductionNuclear factor B (NF-B)/Rel transcription factors represent an ubiquitously expressed family that modulate the expression of genes involved in diverse cellular functions such as stress response, innate and adaptive immune reactions, and apoptosis. Examples include ␤-interferon, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, immunoglobulin light chain, interleukin-2 (IL-2), major histocompatibility complex I, T-cell receptor, A20, inhibitor of apoptosis protein (IAP), and acute phase genes (for recent reviews, see Baeuerle, 1 de Martin et al, 2 and Hatada et al 3 ). Viruses, such as human immunodeficiency virus 1 or human T-cell leukemia virus 1, use NF-B to control the transcription of their own genes and prevent their host cells from undergoing apoptosis. 4 In endothelial cells (ECs), genes dependent on NF-B include, among others, IL-1, IL-6, IL-8, E-selectin, intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), inducible nitric oxide synthase, cyclooxygenase 2, and tissue factor. In cells of the vasculature, NF-B can be activated by inflammatory cytokines, bacterial lipopolysaccharides (LPS), oxidized low-density lipoprotein (LDL), advanced glycation end products, platelet-derived growth factor, and hypoxia/reoxygenation. Several disorders that involve endothelial and smooth muscle cells, such as acute and chronic inflammation and atherogenesis, have been associated with elevated levels of NF-B.The NF-B family includes the mammalian proteins p65 (RelA), RelB, c-Rel, the viral oncogene v-Rel, ...