CD20

CD20 is a non-glycosylated phosphoprotein expressed on the surface of all mature B-cells.

Function
The protein has no known natural ligand and its function is unclear. It is suspected that it acts as a calcium channel in the cell membrane. It is also found on B-cell lymphomas, hairy cell leukemia, and B-cell chronic lymphocytic leukemia.

Clinical significance
It is the target of the monoclonal antibodies rituximab, Ibritumomab tiuxetan, and tositumomab, which are all active agents in the treatment of all B cell lymphomas and leukemias.

FMC7 appears to be a conformational variant.