GRP78 (78-kDa glucose-regulated protein) is essential for cell viability. GRP78/BiP is induced by stress-inducing agents or by conditions that adversely affect endoplasmic reticulum(ER) function, including oxidative stress, chemical toxicity, Ca2+ ionophores, inhibition of the ER Ca2+ -ATPase, inhibitors of glycosylation and hypoxia. GRP78/BiP is critical for maintenance of Ca2+ homeostasis and the prevention of apoptosis. GRP78/BiP levels are reduced in Alzheimer′s disease brains and the decreased expression of GRP78/BiP is found associated with mis-sense mutations in presenilin-1 (PS-1).
