ras

Of biological background, Ras refers to a monomeric, oncogenic guanine nucleotide binding protein (G-protein) associated with the cell membrane of essentially all eukaryotic cells. When activated by binding of a pro-proliferative extracellular ligand to its cellular receptor, Ras releases its guanosine diphosphate in exchange for guanosine triphosphate, thus activating it. It then propagates the proliferation activation signal through a MAP-kinase dependent pathway causing altered gene expression giving rise to the onset of the cell cycle.