Component of the cuticle of the adult fruit fly. Could be involved in thickening of the hard adult cuticle. Detected in the epidermis underlying the head and thorax (including legs and wings), but not in the abdominal epidermis of newly eclosed flies. Expression starts around 72 hours after pupariation, peaks 12 hours after eclosion and decreases thereafter to undetectable levels by 3 days after eclosion. The tetrapeptide (A-A-P-[AV]) repeats found throughout the protein are also present in many proteins constituting the protective envelope of other species.