Arginine fingers are also present in Ras GTPases, where they help cleave GTP to turn Ras off. Ras is a GTPase which functions in signal transduction to regulate cell growth and division. In addition to being positively charged, which helps arginine fingers function as a catalyst, the arginine finger in Ras displaces solvent molecules and creates an optional charge distribution. Like those of dUPTases, the arginine fingers of Ras GTPases are assisted by a magnesium ion. Furthermore, multiple arginine finger residues can all point towards the same point, thus focusing their effect. Mutations affecting the arginine fingers of Ras lead to trouble catalyzing GTP by factors of around two to five orders of magnitude. Thus, as Ras is an oncogene and is activated and deactivated by the hydrolysis of GTP, mutations in Rass arginine finger residues can lead to cancer. Glutamate also plays a role near arginine fingers and is stabilized by the arginines backbone chain carboxyl groups, which are known as knuckles.