MAPT and Alzheimer disease: Considering our data on the striking similarities on the interaction of neurodegeneration-related misfolded proteins (α-syn, tau and amyloid-β[1–42]) with SDCs, along with clinical findings on the increased expression of SDCs in human AD brains suggest that neurodegenerative disorders, especially AD, could be considered as “syndecanopathies”, namely the elevated level SDCs, especially the neuron predominant SDC3, creates favorable environment for fibrillation of aggregation-prone proteins (α-syn and tau or amyloid-β), besides facilitating their cellular translocation into neurons.