EVIDENCE FOR A RAS RAL SIGNALING CASCADE

It is becoming clear that Ras proteins mediate their diverse biologica l functions by binding to, and participating in, the activation of mul tiple downstream targets. Recent work has identified nucleotide-exchan ge factors for Ral-GTPases as the newest members of the set of putativ e Ras 'effector molecules'. This new work has also detected two potent ial downstream targets of Rat proteins, a novel CDC42/Rac GTPase-activ ating protein and a phospholipase D.