Our group studies eukaryotic signal transduction, focusing on how external stimuli control proliferation, differentiation, and homeostasis. Work has centered on defining how mitogen activated protein kinase (MAPK) cascades function in vivo. MAPK cascades form the cores of numerous eukaryotic signal transduction pathways that control growth, differentiation and survival. Misregulation of MAPK cascades is associated with a variety of diseases, including cancer. We use a yeast model system (Figure 1) and genetic, biochemical and cell biological approaches.