MAPT and tauopathy: To this aim we measured entry of pathogenic oligomeric tau in primary human brain endothelial cells (HBEC) and defined the impact of oligomeric tau entry on endogenous native endothelial cell tau phosphorylation, microtubule stability, and critical aspects of brain vascular endothelial cell function, both in vitro and in vivo in mutant human tau transgenic mice modeling tauopathy.