The phosphorylation of tau protein by PKA triggers subsequent tau phosphorylation by GSK-3β at several AD-relevant phosphorylation sites (Thr181, Ser199, Ser202, Thr205, Thr217, Thr231, Ser396 and Ser422) and simultaneously inhibits tau phosphorylation at Thr212 and Ser404. This evidence concerns the gene GSK3B and Alzheimer disease.