A monomeric G-protein ( also known as small G protein or small GTPases, is the umbrella term for a family of signal transducing proteins. These comprise of: Rab, Arf, Ras, Ran and Rho, which are also vital in the growth of cells, as well as cell transport, motility, cytokinesis and cell differentiation . Monomeric G proteins comprise of two forms, 1.) an 'inactive' form in which the monomeric G-protein is bound to GDP (guanosine diphosphate), and 2.) In order to activate the inactive form of monomeric G-protein, a guanine exchange factor is needed. 3.) the 'active' form in which the Monomeric G-protein is bound to GTP ( guanosine triphosphate). Notably, monomeric G-proteins are small (ranging around 20-25 kDa) compared with larger types of G protein like heterotrimeric proteins (which are typically 30-35 kDa) .