3',5' cyclic adenosine monophosphate (cAMP)-regulated guanine nucleotide exchange factors Epac1 (cAMP-GEFI) and Epac2 (cAMP-GEFII) activate the ras family GTPases Rap1 and Rap2 by promoting GTP binding in a cAMP-dependent manner (1,2). Eukaryotic cAMP is a second messenger that induces physiological responses such as gene expression, growth, differentiation, secretion and neurotransmission (3). Human EPAC2 contains at least 31 exons and maps to chromosome 2q31 (4). The 4.4-kb Epac2 transc