CD20 is expressed on all stages of B cell development except the first and last; it is present from late pro-B cells through memory cells, but not on either early pro-B cells or plasma blasts and plasma cells. It has no known natural ligand and its function is to enable optimal B-cell immune response, specifically against T-independent antigens. It is suspected that it acts as a calcium channel in the cell membrane. It has been shown that CD20 plays a role in the microenvironmental interactions of B cells. [Wiki]

Recombinant CD20 antibody with azide can be stored at 2-8°C. The azide-free format should be aliquoted and stored at -20°C or colder.