In the wing pouch, EcollacZ^kek1-15A6 is expressed as a broad stripe straddling the A/P boundary in the L3 and L4 intervein region and also in the hinge and the notum. EcollacZ^kek1-15A6 is expressed in the presumptive hinge of the haltere pouch.

Expression of the kek1 lacZ reporter which mimicks endogenous transcript expression in the embryo is detected in the vein primordia and the L3/L4 intervein region in the wing disc. kek1-lacZ is also detected posterior to the morphogenetic furrow in the developing eye disc.

Enhancer trap expression is first detected at stage 10 in a few cells per segment in the dorsal midline of the CNS. By early stage 12, the midline staining has evolved to a ventral position. The stained midline cells are thought to include the VUM neurons. By stage 12, expression is seem in many CNS neurons and is maintained through larval development. Expression is also seen in a small subset of ventral and lateral cell clusters of the PNS and in the cap cells in the abdominal segments. In the head region, expression is seen in both neural and nonneuronal cells of the antenno-maxillary complex. Enhancer trap expression was observed in larvae in all imaginal disc while they are undergoing patterning. In the eye-antennal disc, expression is found in the differentiating retinal epithelium, from the posterior border up to several rows behind the morphogenetic furrow, as well as in the presumptive ocelli and ocellar bristles. Dynamic expression is observed during patterning of the follicle cell epithelium in the ovary. During oogenesis, weak expression in nurse cells and stronger expression in columnar follicle cells surrounding the oocyte is seen. By stage S7, expression is apparent in follicle cells at the posterior pole surrounding the oocyte. By stage 9, the posterior expression has disappeared and expression is strong in follicle cells above the oocyte nucleus. This pattern reflects the onset of dorsoventral polarity in the egg chamber and at stage S9 the expression occurs in a gradient. Expression is also seen in border follicle cells.