ABCB1 and multiple sclerosis: Next to the presence of complex TJs, an additional property of the BBB is the presence of specific endothelial transporters, such as the efflux pump P-glycoprotein (P-gp), which actively removes unwanted compounds from the brain.178 Interestingly, P-gp expression was reduced in BMECs in active lesions of multiple sclerosis patients179 and P-gp transport function was significantly reduced during EAE in rats,179 suggesting reduced P-gp function at the BBB in multiple sclerosis.