During development of the peripheral nervous systems, targets of innervation provide neurotrophic factors that support survival and growth. Conversely, neurons competing for innervation of these same targets may release competition factors that accelerate apoptosis of “losing” neurons. The Pierchala laboratory investigates death receptor complexes, such as p75, that are involved in developmental competition, as well as neurotrophic factor receptors, such as the GDNF receptor RET. Interestingly, these two receptors associate physically in sympathetic neurons and can trigger either survival or death, depending upon which ligand predominates. The mechanisms by which apoptotic and survival pathways integrate and cooperate to regulate neural populations is an ongoing area of investigation.