Epac: a new cAMP target and new avenues in cAMP research

Five years ago, Epac - a guanine nucleotide exchange factor for the Ras-like small GTPases Rap1 and Rap2 - was found to be a new target of cyclic AMP, which opened up new avenues for cAMP research. Structural analysis of the cAMP-binding domains of Epac2 has identified a unifying mechanism for how cAMP activates proteins, and the design and synthesis of an Epac-specific cAMP analogue has paved the way for future discoveries.