Another protein, the mitogen-activated protein kinase (MAPK), orchestrates diverse events related to AD, such as tau phosphorylation, ROS, neurotoxicity, neuroinflammation, and synaptic dysfunction, and there is cross-talk between the MAPK signaling pathways and the UPR; moreover, mitochondria, which control so many aspects of cellular metabolism, are physically connected with the ER through specialized proteins in a region that is called the mitochondria-associated ER membrane (MAM). This evidence concerns the gene MAPT and Alzheimer disease.