MAPT and Alzheimer disease: The Tau protein in AD brainsexists in three distinct forms: a normal cytosolic form, a solublehyperphosphorylated form, and an insoluble paired helical filamentform.55 Furthermore, the Tau from AD patientsis also known to contain other post-translational modifications, andit is not understood how PTMs regulate the (in vitro) formation of AD filaments or which phase transformations are relevantfor PHF formation on full-length Tau.