CD157 also known as BP-3 Alloantigen or Bone marrow Stromal cell antigen-1 (BST-1), is a 38-48 KDa differentially glycosylated glycosylphosphatidylinositol (GPI) anchored cell surface glycoprotein. CD157, like CD38 belongs to a family of genetically related pleiotropic ectoenzymes. The CD157 antigen is expressed on thymocytes, bone marrow B cells, neutrophils, macrophages, stromal cells, intestinal epithelial cells, the collecting tubules of the kidney and reticular cells in lymph nodes. The CD157 receptor has ADP ribosyl cyclase and cyclic ADP ribose hydrolase biochemical activities. Studies show CD157 is a receptor that induces reorganization of the cytoskeleton and significant changes in cell shape. CD157 is also a mediator of neutrophil adhesion and migration. Signals mediated by CD157 act through modulation of cytosolic [Ca2+]. CD157 is also involved in cellular adhesion to the extracellular matrix.Synonyms: ADP-ribosyl cyclase 2, BST-1, Bone marrow stromal antigen 1, Cyclic ADP-ribose hydrolase 2, cADPr hydrolase 2