– B-lymphocyte antigen CD20 or CD20 is an activated-glycosylated phosphoprotein expressed on the surface of all B-cells beginning at the pro-B phase (CD45R , CD117) and progressively increasing in concentration until maturity.CD20 is the target of the monoclonal antibodies rituximab, ocrelizumab, obinutuzumab, ofatumumab, ibritumomab tiuxetan, tositumomab, and ublituximab, which are all active agents in the treatment of all B cell lymphomas, leukemias, and B cell-mediated autoimmune diseases. CD20 Protein, Human, Recombinant (His & Avi), Biotinylated is expressed in E. coli expression system with C-His-Avi tag. The predicted molecular weight is 16.8 kDa and the accession number is P11836-1.