Cells are highly responsive to signals from their environment. These signals include growth factors, hormones, or even neuronal firing. The sensing and processing of these signals are carried out by molecular circuits within the cell which detect, amplify and integrate these environmental cues into a specific response. Ras-related GTP-binding proteins function as GTP/GDP- regulated “switches” and are widely utilized in cellular response pathways. Ras G- proteins respond to extracellular stimuli by exchanging GTP for bound GDP, thereby triggering intracellular signaling cascades through their GTP-dependent interaction with a variety of target molecule(s) to produce a characteristic cellular effect. My laboratory is interested in deciphering the role of Ras GTPases in various cellular paradigms, as Ras family G-proteins play key roles in the ontogency of cancer, diabetes, and heart disease as well as the processes of neuronal survival and axonal growth. Because we have studied the function of several GTPases in some detail, I will review some of our findings in this area and briefly outline our current research interests.