Ras-related protein Rap-2b, also known as RAP2B, belongs to a family of RAS-related genes. Unlike normal ras proteins that have a nontransforming glutamine residue at aa 61, Rap2B has a threonine residue in that position. This change makes the intrinsic GTPase activity for Rap2B lower, thereby allowing it to exist in the activated state for a longer period of time than normal ras proteins. RAP2B is a platelet protein that is activated by thrombin and involved in platelet activation. RAP2B may be a novel candidate oncogene that plays important roles in carcinogenesis through activation of NF-kappaB pathway.