Stages in the development of CA3 neurons illustrate how the 7 nicotinic receptor (nAChR) can contribute to axon growth. Protein expression of 7 and G protein-regulated inducer of neurite outgrowth 1 (Gprin1) peaks between E18 and P10 in rodents. This time period is characterized by significant changes in synaptic structure and circuit development in the hippocampus. 7-mediated elevations in intracellular calcium within the growth cone (GC) are proposed to serve as stop' signal for axon growth, thereby possibly contributing to synaptic pruning. Interaction with Gprin1 ensures localization of 7 at the GC, and mediates coupling to a G(o), GAP-43, and CDC42 signaling pathway.