CD157 is a glycosyl phosphatidylinositol anchored membrane protein that belongs to the CD38 family. CD157 was discovered in a bone marrow stromal cell line where it facilitates preBcell growth. Along with CD38, CD157 is a bifunctional ectoenzyme that exhibits both ADP-ribosyl cyclase and cyclic ADP ribose hydrolase activities. It may play a role in rheumatoid arthritis (RA) due to its enhanced expression in RA-derived bone marrow stromal cell lines. CD157 has been predicted to function as a cell surface receptor and an immunoregulatory molecule. CD157 was originally identified as a bone marrow stromal cell molecule (BST-1) with a glycosylphosphatidylinositol (GPI) anchor to bind to the cell surface. CD157 is prevalently expressed by cells of the myeloid lineage. CD157 could act as a receptor with signal transduction capability. Further, it regulates calcium homeostasis and promotes polarization in neutrophils and mediates superoxide (O2?) production in the human U937 myeloid line.
