RESCUE OF A DROSOPHILA NF1 MUTANT PHENOTYPE BY PROTEIN-KINASE-A

The neurofibromatosis type 1 (NF1) tumor suppressor protein is thought to restrict cell proliferation by functioning as a Ras-specific guano sine triphosphatase-activating protein. However, Drosophila homozygous for null mutations of an NF1 homolog showed no obvious signs of pertu rbed Ras1-mediated signaling, Loss of NF1 resulted in a reduction in s ize of larvae, pupae, and adults. This size defect was not modified by manipulating Ras1 signaling but was restored by expression of activat ed adenosine 3',5'-monophosphate-dependent protein kinase (PKA). Thus, NF1 and PKA appear to interact in a pathway that controls the overall growth of Drosophila.