FLRG (follistatin-related gene, follistatin-like-3 or FSTL3) is a member of the follistatin-module protein family, which is composed of extracellular matrix-associated glycoproteins thought to act in a paracrine manner to bind morphogens or growth/differen-tiation factors and regulate their activity during development. The FSTL3 protein contains 2 potential N-glycosylation sites and the predicted mass of the unmodified core protein is 27 kDa. FLRG is expressed in a wide range of human and murine adult tissues and its expression seems to be tightly regulated during murine embryogenesis. Immunohistochemistry reveals the presence of FLRG in the basement membrane between the dermis and the epidermis and around blood vessels.