MAPT and juvenile Huntington disease: More recently, the active form of the enzyme, which represents half or more of the total GSK3β in cultured cells [63], was also demonstrated to contribute to Tau phosphorylation in neuroblastoma cells exposed to Aβ [29] and to have a contributory role in the pathogenesis of Parkinson’s and Huntington ́s diseases by influencing Tau protein phosphorylation [64,65].