INS and type 2 diabetes mellitus: Corroborative evidence for this phenomenon comes from studies on pancreatic islet sections from patients with T2DM, whose β cells show two classic signs of ER stress pathway activation—an increase in mRNA levels of ER stress markers, including the pro-apoptotic factors, ATF3 and CHOP, and expansion of the ER due to accumulation of proinsulin (58).