Component of the rigid cuticle of the larva and pupa of Hyalophora cecropia. Expressed in larval wing disc, forewing disc, diapausing wing, adult wing, and in very low amounts in fat body and testes. Mostly present in young pupal wings and larval tubercles. Faintly present in younger than 24 hours old pupal forewing and hindwing. Weakly detected in hindwing and tubercles.