MAPT and Alzheimer disease: An endogenous Wnt inhibitor, Dickkopf-1 (Dkk1), which disrupts Wnt-induced Fz/LRP complex formation[99], is increased in human postmortem AD brains[100] and mouse model AD brains[101], where Dkk1 has been found to co-localize with active GSK-3 and phospho-tau.