OCLN and Cerebral ischemia: When exposed to focal cerebral ischemia induced by transient intraluminal MCAO, mice on Western diet exhibited increased activation of calpain-1/2 and matrix metalloproteinase-2/9, overactivation of RhoA and its guanine exchange factor leukemia-associated guanine exchange factor, and downregulation of the tight junction protein occludin in cerebral microvessels, resulting in increased blood–brain barrier permeability and brain swelling [21].