====== Cluster of differentiation ======

The cluster of differentiation (also known as cluster of designation or classification determinant and often abbreviated as [[CD]]) is a protocol used for the identification and investigation of [[cell surface]] molecules providing targets for immunophenotyping of cells.

In terms of physiology, CD molecules can act in numerous ways, often acting as receptors or ligands (the molecule that activates a receptor) important to the cell. A signal cascade is usually initiated, altering the behavior of the cell (see cell signaling). Some CD proteins do not play a role in cell signaling, but have other functions, such as [[cell adhesion]]. CD for humans is numbered up to 371 (As of April 2016).

see [[CD4]].