A final argument explaining the lack of tauopathy in Tau.4R mice, and by extension in the bigenic Tau.4RxGSK3β mice, was our most recent finding of the strict axonal location of Tau.4R, as opposed to the somatodendritic delocalization of Tau.P301L in transgenic mouse brain [92, 109]. This evidence concerns the gene MAPT and tauopathy.