1,2-dehydro-N-beta-alanyldopamine precursor N-β-alanyldopamine (NBAD) is synthesized in the cytosol of epidermal cells from dopamine. During pre- or post-ecdysis, NBAD is transported into the cuticular matrix and converted sequentially to the corresponding ortho-quinone, para-quinone methide, and hydro-NBAD. These various reactive products react with cuticular proteins and chitin, forming adducts and crosslinks that result in the hardening of the cuticle, a process known as sclerotization. In addition, NBAD derivatives confer a brown color to the cuticle. (Adapted from PMID:19932179 and FBrf0246618.)