Reporter expression is observed in some muscle cells at embryonic stage 13 including cardial cells and in almost all cardial cells in the heart region of the dorsal vessel and in some cardial cells in the aorta region in stage 16 embryos. It is also expressed in the hindgut.

Enhancer trap expression is first observed in embryos at stage 9 in cephalic neuroblasts. Expression continues weakly in the CNS throughout embryogenesis and includes sheath cells. Expression in the PNS is first observed at stage 11. By stage 14, intense staining is seen in ventral and lateral sense organs along the trunk and in the antennomaxillary complex. During head involution, intense staining is observed in the antennomaxillary complex and in the labral sense organs. In larvae, staining is observed in a restricted set of cells in the optic proliferation centers, the cerebral hemispheres and the ventral ganglion. The cells are probably not neuroblasts and may be glia or sheath cells. Enhancer trap staining is observed in all of the imaginal discs except the labial disc. Staining in the wing disc occurs in regions that will give rise to the adult wing blade, the scutellum, and the mesopleura. In the eye disc, staining is turned on immediately behind the morphogenetic furrow. In adults, enhancer trap expression is observed in discrete regions of the adult brain including cell bodies in the suboesophageal ganglion, nuclei lying medial to the antennal neuropile and within the lobular plate, cell bodies in the calyx of the mushroom bodies and cell bodies in the protocerebrum. Staining is also observed in the proboscis in two cells per sensillum that are thought to be the sheath cell and the glial cell. The sacculus and a subset of cells in the olfactory sensilla are stained as well as photoreceptor cells and restricted cells in the ventral ganglion. Finally, staining is observed in the jump muscle and in hairs located all over the adult cuticle.