PGP and Alzheimer disease: While our current review indicates that available information on transporter regulation in the BBB in AD is focused on P-gp, two excellent reviews list transporter such as ENT1, OATs, OATPs, GLUTs, as well as BCRP, MRP1, ABCG1/4, and ABCA1/7, to be partially involved, either directly or indirectly, in the pathogenesis of AD [84,85].