MAPT and Alzheimer disease: Knockdown of Ext1/Ext2 has been shown to inhibit uptake of recombinant monomeric and fibrillar 2N4R tau and of human tau oligomers extracted from both AD and dementia with Lewy bodies brains in HEK293 cells, primary cortical and hippocampal neurons as well as human iPSC derived neurons (Holmes et al., 2013; Puangmalai et al., 2020; Rauch et al., 2018; Stopschinski et al., 2018).