Sialic acid-binding Ig-like lectin 9(Siglec 9) is expressed by peripheral blood leukocytes (neutrophils and monocytes but not eosinophils), and found in liver, fetal liver, bone marrow, placenta, spleen and in lower levels in skeletal muscle, fetal brain and so on. It is a putative adhesion molecule that mediates sialic-acid dependent binding to cells. It also binds to alpha-2,3- or alpha-2,6-linked sialic acid. The sialic acid recognition site may be masked by cis interactions with sialic acids on the same cell surface.