MAPT and Alzheimer disease: To determine whether this is also true without overexpression of LRRK2 and whether LRRK2 kinase inhibition can reverse this effect, we injected LRRK2G2019S KI mice [21] and their wild-type littermates with tau PHFs extracted from AD brains (Additional file 1: Table S1)[24] at 3 months of age unilaterally in the hippocampus and overlaying cortex (Fig. 1a).