MAPT and Alzheimer disease: In addition, preblocking of Heparan Sulfate Proteoglycans (HSPG) with heparin (20 μg/mL for 3 h, which inhibits tau uptake) almost mitigated the effect of Mono- (Supplementary Figure S3g–i) and AggTau (Supplementary Figure S3j–l) on sAD and fAD astrocytes, when compared to heparin-untreated cells (Suplementary Figure S3a–f), suggesting a tau-specific effect on AD-derived astrocytes.