Rheb^26.2/Rheb^3M2 animals die as pupae. The imaginal discs from larvae of this genotype are smaller than wild-type, roughly in proportion with their small body size. The salivary glands of these animals are even more severely reduced in size. Somatic clones of Rheb^3M2 homozygous cells in the eye are able to differentiate into the various cell types of the eye, but are greatly reduced in size (as reflected by a 72% reduction in rhabdomere area in tangential sections). It is clear from mosaic ommatidia that this reduction in cell size is strictly cell-autonomous.