CD20: a gene in search of a function.

CD20 is a signature B-cell differentiation antigen. The function of CD20 is unknown, although it is thought to be involved in B-cell activation, regulation of B-cell growth, and transmembrane calcium flux. This review covers several topics important for understanding CD20 biology. These topics include the expression pattern and transcriptional regulation of the CD20 gene, the structure of the protein and its interaction with other cell surface molecules, as well as CD20 phosphorylation and putative functions. An understanding of CD20 function from signal transduction to biological implications may prove important for the mechanistic understanding of the treatment of certain types of cancer.