FSTL3, follistatin-like 3, is a secreted glycoprotein of the follistatin-module-protein family. FSTL3 is expressed in the placenta and may play a role in regulating the extracellular matrix of the placenta. FSTL3 is a binding protein for activin and BMP2 and thought to regulate activin and myostatin during normal adult metabolic homeostasis. FSTL3 may also contribute to bone formation by inhibiting osteoclast differentiation from hematopoietic precursors. A chromosomal aberration involving FSTL3 is found in a case of B-cell chronic lymphocytic leukemia.Synonyms: FLRG, FSTL3, Follistatin-like 3, Follistatin-related gene protein