One of the three G-protein-linked cellular signalling protein (see also k-ras and n-ras). All three members of the ras family produce a 21kD protein and are distinguished by superscripted suffix, i.e. p21h-ras. It is a proto-oncogene in that the wild-type protein product serves a physiological role, but mutations result in an oncogene due to inappropriate celllular signalling.
Congenital mutations may result in Costello syndrome.