Objective: Fluid shear stress is a physiologically important regulator of endothelial function and acts, at least in part, via the PKA-dependent activation of the endothelial nitric oxide synthase (eNOS). PKA activity is tightly controlled by AKAPs that tether the type 2 regulatory subunit of PKA (PKA- RII). AKAP12 is reported to promote quiescence in various cell types, but little is known about its role in the resting or activated endothelium. We aimed to determine whether or not fluid shear stress influences the expression and/or activity of AKAP12 in endothelial cells (EC). Methods: Primary human umbilical vein EC were cultured under static conditions or subjected to fluid shear stress (12 dyne/cm²) for 24 to 72 hours. AKAP12 mRNA and protein expression were assessed by RT-qPCR and Western blotting respectively. The cellular localisation of AKAP12 was detected by immunofluorescence in cultured EC and in murine aortae. Results: AKAP12 mRNA was significantly (P<0.01) increased in EC after exposure to shear stress for 24 hours. Protein expression rose continuously at least up to 72 hours. In resting EC, AKAP12 showed a diffuse cytoplasmatic distribution, but concentrated in the perinuclear region. After 24 hours exposure to fluid shear stress, the cells adopted a spindle shaped conformation and AKAP12 was found at the cell-cell junctions, which was sensitive to the PKA inhibitor H89 (10 mM). In murine aortae we made similar observations: In regions of laminar flow en face staining revealed an AKAP12 distribution at the cell margins of the spindle shaped EC. In regions of oscillatory flow AKAP12 remained around the nucleus. Conclusion: Taken together, our findings indicate that fluid shear stress enhances the endothelial expression of AKAP12 and its presence at cell-cell junctions. These results suggest a role for AKAP12 in the endothelial response to shear stress and therefore in the maintenance of endothelial homeostasis.