Anterior Gradient 2 (AGR2), an ER stress-inducible protein, has been reported to be localized in endoplasmic reticulum (ER) and its level is elevated in numerous metastatic cancers. Recently, it has been demonstrated that AGR2 is involved in the control of ER homeostasis. However, the molecular mechanism how AGR2 regulates ER stress response remains unclear. Herein we show that AGR2 homo-dimerizes through an intermolecular disulfide bond. Moreover, dimerization of AGR2 attenuates ER stress-induced cell death through the association with B1P/GRP78. Thus, these results suggest that dimerization of AGR2 is crucial in mediating the ER stress signaling pathway. (C) 2012 Elsevier Inc. All rights reserved.