Description: The SJ25C1 monoclonal antibody reacts with human CD19, a 95 kDa transmembrane glycoprotein. CD19 is expressed by B cells during all stages of development excluding the terminally differentiated plasma cells. Follicular dendritic cells also express this molecule. CD19, along with CD21, CD81, Leu13, and MHC class II, form a multimolecular complex that associates with the BCR. Signaling through CD19 induces tyrosine phosphorylation, calcium flux, and proliferation of B cells.