MAPT and Alzheimer disease: Perea et al. (2019) reported that the uptake of monomeric tau by primary astrocytes was unaffected by pre-treatment of the cultures with heparin or heparinase, indicating the astrocytes took up tau via an as of yet unidentified HSPG independent pathway. In a comparative study of the uptake of brain derived tau oligomers from patients with AD, PSP, and DLB, Puangmalai et al. (2020) found that the knockout of the HSPG biosynthetic enzyme exostin-2, as well as treatment with HSPG antagonists abolished the uptake of AD and DLB derived tau oligomers as expected.