Collagen type II is the most abundant protein of cartilage matri, Xenopus/Amphibian,. Two isoforms e, Xenopus/Amphibian,ist and collagen type IIA is involved in early development of cartilage in embryos. The collagen is produced from type II procollagen when two teloterminal propeptides are digested from the procursor and released into the circulation. Procollagen type II N-terminal propeptide (PIIANP) is considered a marker of cartilage synthesis and the normal concentration in serum is appro, Xenopus/Amphibian,imately 30 ng/ml. This antibody is specific for human PIIANP.