The enhancer trap staining pattern resembles that of 18w during germ band extension but becomes more complex due to the perdurance of the β-gal enzyme. In stage 14-16 embryos, expression is observed in ectodermal stripes that are 4-5 cells wide in each segment. Expression is also observed in most of the developing tracheal tree, salivary glands, anal pads, dorsal vessel, hindgut, pharynx, posterior spiracles, a small cluster of cells in each metamere of the CNS, and in some of the ventral muscles.

During oogenesis, stage S2-S6, expressed in stalk cells and adjacent follicle cells; during stage S8, expressed in all columnar follicle cells: during stage S10, there is a loss of expression at the posterior pole; stage S14, expression in the dorsal appendages, the operculum and scattered cells in the dorsoanterior.