CD20 is a 33-37 kDa type-III non-glycosylated phosphoprotein spanning the cell membrane four times therefore called TM4. CD20 antigen is expressed on pre-B cells, resting/activated B cells and corresponding neoplastic B cells, but is absent from plasma cells. CD20 regulates B lymphocyte activation and proliferation. Product Cat. No. 252263 is the FITC conjugate of Cat. No. 250586.