The long term goals of this research are to understand the mechanisms by which NFl controls growth using the Drosophila peripheral nerve. This system is advantageous because we can apply a number of powerful molecular genetic methodologies that are not available in other systems. The aims of this project address three specific aspects of growth control. In our first aim, we asked if NF1 acts downstream of a G protein to exert its effects. Although we have found that overexpression of amnesiac (amn) and Gas, each enhance the effects on glial growth of expression of RasV12, no equivalent effect of NFl overexpression was observed. These data support the hypothesis that amn acts through Gas and presumably PKA to promote perineurial glial growth. However, a role for NF1 in this process is currently unclear. In our second task, we proposed to test further the hypothesis that increased neurotransmitter release from motor neurons (or increased neurotransmitter persistence) affects perineurial glial growth. All data collected for this task was negative. For task three, we found that increased perineurial glial growth driven by RasV12 expression is, indeed, associated with the formation of extra perineurial cells.