In this study, we used in vitro and in vivo systems to demonstrate that (i) AKAP12 is upregulated in cerebral endothelial cells after ischemic stress, (ii) AKAP12 deficiency increases endothelial permeability through the disruption of tight junction proteins, and (iii) Rho kinase signaling is upregulated by AKAP12 deficiency, which results in the exacerbation of endothelial dysfunction after stroke. The gene discussed is AKAP12; the disease is endothelial dysfunction.