gbb is observed to be expressed in somatic cells of the testis.

gbb is observed to be expressed in somatic cells of the germarium.

The gbb transcript is detected at low levels thoughout the imaginal disc tissue, with higher levels of expression in the posterior region and the wing pouch of the wing disc, anterior to the morphogenetic forrow and in the medial regions of the eye-antennal disc, and in the posterior and ventral anterior regions of the leg disc.

gbb protein is first detected after stage 7. By stage 10, gbb protein expression is observed in the stomodeal invagination and the mesoderm. Expression at stage 12 is found in the anterior and posterior midguts and in the visceral mesoderm. In later embryos, staining is observed in the foregut, hindgut, anterior and posterior midguts.

gbb is expressed throughout development with peaks in 4-12hr embryos, late larvae, and pupae. It is expressed in adult males at high levels but not in females.

At the larval neuromuscular junction, extracellular gbb protein concentrated in a ring of punctate domains around boutons.

Mad protein accumulates in motor neuron nuclei beginning at embryonic stage 15.

The gbb protein is detected at low levels thoughout the imaginal disc tissue, however, distinctly lower levels of protein are detected along the morphogenetic forrow of the eye-antennal disc, along the anterior-posterior boundary of the wing disc, and in the dorsal anterior region of the leg disc.