The clone 2H7 recognizes the large extracellular loop of human CD20, mapped to the peptide sequence YNCEPANPSEKNSPST. CD20, a 33-36 kDa non-glycosylated type 1 transmembrane protein, is expressed by developing, resting and mature B cells, some follicular dendritic cells, and a small subset of mature T cells. B cell CD20 expression is lost upon differentiation into plasma cells. Functionally, CD20 activation contributes to B cell activation, proliferation, and differentiation