Recent evidence using tau pT231-P232 rotamer-specific antibodies [199] suggests that the cis-, but not the trans-, rotamer is an early conformer associated with AD progression; that PIN1 restores the ability of cis-pT231-Tau to promote microtubule assemble; that cis-pT231-Tau is more stable and more prone to aggregation than trans-pT231-Tau; that cis-, but not trans-, pT231-Tau correlates with NFTs in the AD hippocampus; that PIN1 promotes cis-to-trans isomerization of pT231-Tau in AD mouse models. Here, MAPT is linked to Alzheimer disease.