Component of the cuticle of the larva of tobacco hornworm. Seems to participate in the formation of 5- to 10-fold thinner lamellae in the endocuticle. Specific to the epidermis. Expressed in all the epidermal cells of day 3 larvae except for the bristle cells and those at the muscle attachment sites. Expressed late on the penultimate day of feeding in the fifth larval instar. Highest levels throughout the final day of feeding. Barely detectable by the day of wandering. Expression stops when the metamorphosis begins. In day 1 epidermis, by exposure to hydroxyecdysone in vitro without juvenile hormone.