Microfibril-associated glycoprotein 3 (MFAP3) and microfibril-associated glycoprotein 3-like (MFAP3L) are classified as microfibril-associated glycoproteins (MAGPs) due to their small size and localization to microfibrils [, , ]. However, MFAP3L has been found in the nucleus and may function as a nuclear kinase []. Homologues are known in vertebrates.