Overexpression of CREB protein protects from tunicamycin-induced apoptosis in various rat cell types.

Endoplasmic reticulum (ER) stress plays an essential role in unfolded protein response induced apoptosis contributing to several pathological conditions. Glycogen synthase kinase-3β (GSK-3β) plays a central role in several apoptotic signaling, including ER stress, as the active form of GSK-3β induces apoptosis. The phosphorylation of cAMP responsive element (CRE) binding protein (CREB) Ser-133 (S133) residue is the end-point of various signaling pathways, like growth factor signaling, while the Ser-129 (S129) residue is phosphorylated by GSK-3β.