MAPT and Alzheimer disease: Hyperphosphorylation of tau (which causes AD) is a result of abnormal activation of GSK3 and other kinases, which most likely happens due to initial Aβ toxicity or soluble Aβ oligomers (toxic to synapses), and has been reported to induce neuronal apoptosis, mediated by p38MAPK and c-JUN amino-terminal kinases or JNKs [73,74,75,76,77,78,79,80].