Regulator of calcineurin 1 (RCAN1) is located on the Down syndrome critical region (DSCR) locus in human chromosome 21. In this study, we investigated the functional role of RCAN1 in the reactive oxygen species (ROS)-mediated neuronal death signaling. We found that RCAN1 was able to protect the cells from H2O2-induced cytotoxicity. The expression of RCAN1 caused an inhibition of the H2O2-induced activation of mitogen-activated protein kinases (MAPKs) and AP-1. In contrast, RCAN1 significantly enhanced the activity of cAMP response element-binding protein (CREB). Furthermore, RCAN1 induced the expression of the CREB target gene, Bcl-2. Consistently, knockdown of endogenous RCAN1 using shRNA down regulated the phosphorylation of CREB and the expression of Bcl-2, which protects the cells from H2O2-induced cytotoxicity. Our data provide a new mechanism for the cytoprotective function of RCAN1 in response to oxidant-induced apoptosis. J. Cell. Biochem. 114: 1115–1123, 2013. © 2012 Wiley Periodicals, Inc.