Enhancer trap expression is first detected in the eye disc at the onset of the third instar at which time expression occurs in a gradient increasing from anterior to posterior. Enhancer trap expression continues in the third instar in nuclei anterior to, within, and posterior to the morphogenetic furrow. Expressed occurs in most if not all cells of the disc epithelium. In embryos, enhancer trap staining is seen in the region of the optic lobe primordia and in segmentally reiterated patches that straddle the segmental furrows.

In eye disc, expression during early third instar exhibits a gradient, increasing from anterior to posterior and at the edges of the epithelium. By late third instar, expressed in most, if not all, cells of the disc epithelium.