INS and type 2 diabetes mellitus: The UPR pathway integrates many biological processes known to play a role in the pathogenesis of type 2 diabetes such as the transport of glucose across the cell membrane, insulin-stimulated glucose uptake by the cell, glucose and energy metabolism, inflammation, autophagy, apoptosis, ER-associated ubiquitin- and proteasome protein degradation, glutathione and sulfur amino acid metabolism.