Homozygous clones in the eye disc result in strong overgrowth of the eye.
Hemizygotes die as late embryos or early first instar larvae. Homozygous mutant clones in the eye bulge out from the eye surface. Ommatidia sometimes fuse interommatidial bristles are abnormal, particularly (but not exclusively) in the dorsal half of the eye. Mutant clones typically contain at least twice as many ommatidia as their wild type twin spots. The largest clones can form a hyperplastic tumor-like overgrowth, though this phenotype is less severe than for tumor suppressor mutations. Within each ommatidium cell type specification seems normal. Cell bodies of mutant photoreceptors are enlarged compared to wild type neighbors, and the rhabdomeres are misshapen. The cell size and rhabdomeric phenotypes are cell autonomous. Homozygous mutant clones in the wing reveal an increase in cell size. Wing hairs are occasionally duplicated and crossvein formation is abnormal. Occasional extra wing vein material develops. Longitudinal veins are rarely affected.