Guanine-nucleotide dissociation stimulator, CDC24, conserved site Ras proteins are membrane-associated molecular switches that bind GTP and GDP and slowly hydrolyze GTP to GDP [<cite idref="PUB00004087"/>]. The balance between the GTP bound (active) and GDP bound (inactive) states is regulated by the opposite action of proteins activating the GTPase activity and that of proteins which promote the loss of bound GDP and the uptake of fresh GTP [<cite idref="PUB00004162"/>, <cite idref="PUB00001017"/>]. The latter proteinsare known as guanine-nucleotide dissociation stimulators (GDSs) or also asguanine-nucleotide releasing (or exchange) factors (GRFs). Proteins that act as GDS can be classified into at least two families. One of these families is currently known to group the CDC24 family of proteins.