A glutamic acid residue at position 31 of ras protein is essential to the signal transduction for neurite outgrowth of PC12 cells and the stimulation of GTPase activity by GAPras. - Shirouzu,MS.; Fujita-Yoshigaki,J.; Ito,Y.; Koide,H.; Nishimura,S.; Yokoyama,S. (Oncogene, 1992)