Tau is a microtubule associated protein mostly associated with Alzheimer's disease. As such it makes sense that abnormalities in tau would implicate which of the following processes in neurodegeneration?
1) autophagy
2) Endoplasmic Reticulum (ER) stress and the unfolded protein response (UPR)
3) the ubiquitin proteasome system (UPS)
4) axonal transport