Axonal growth is one of the hallmarks of neuronal polarization, and requires axonal membrane expansion by exocytosis of plasmalemmal precursor vesicles (PPVs) at the nerve growth cone. We have demonstrated that IGF-1 stimulates the regulated exocytosis of PPVs via activation of the PI3k pathway. Few details are known, however,   about the PPVs targeting mechanisms. Results from our laboratory show that the cascade critical for the regulation of membrane expansion in neurons includes TC10 and the exocyst complex. We have also examined the role of growth factors in polarization and established that IGF-1 is the growth factor initiating axonal specification and that a  particularly early event, in neurons that do not yet exhibit a discernible axon, is the segregation of activatable IGF-1 receptors in one neurite. Activation of the IGF-1 receptor requires its insertion into the plasmalemma, controlled by TC10 activity and the exocyst complex. Because IGF-1 activates TC10 and triggers exocyst assembly it may regulate the insertion of its own receptor. This is a positive-feedback mechanism that could rapidly amplify the membrane expansion response to IGF-1. We propose, therefore, that the process of IGF-1 receptor mobilization to neurite plasmalemma / receptor activation  / and further membrane expansion may be (one of) the self-reinforcing mechanism(s) necessary for axonal specification.