CD45R, also known as B220, is a receptor-type protein tyrosine phosphatase glycoprotein. It is crucial in lymphocyte development and antigen signaling, serving as an important regulator of Src-family kinases, promotes cell survival by modulating integrin-mediated signal transduction pathway and is also involved in DNA fragmentation during apoptosis. CD45R expression also identifies a subset of murine bone marrow cells able to form osteoclast-like cells.
