Guanine-nucleotide-binding proteins are molecular switches that transduce the signals received at a cell's surface to elicit a biological response from the proteins inside. There are two types of G protein — the heterotrimeric G proteins and the small GTPases. New research shows that a well-known small GTPase called Rap1 is regulated by a heterotrimeric G protein, via a GTPase-activating protein called Rap1GAPII.