The relationship between ER stress and its effect on the pathophysiology of depression was investigated by Behnke et al. [12] Higher expression levels of GRP78, GRP94, and calreticulin in a post-mortem examination were found in the temporal cortex of MDD patients with major depressive disorders who died of suicide compared to those of MMD patients after non-suicidal deaths. This evidence concerns the gene HSPA5 and depressive disorder.