The MY31 antibody reacts with human CD56, also known as the neural cell adhesion molecule (NCAM), a glycoprotein which is a member of the immunoglobulin superfamily. The 140 kDa isoform of CD56 is expressed on human NK cells and NK-T cells, with increased expression levels on activated NK lymphocytes. The CD56 antigen is also expressed by neurons and is reported to play a role in nervous system development and neural cell-to-cell adhesion. Clone MY31 also reacts with a subset of CD14+ monocytes in non-human primates, and is reported to be cross-reactive with Chimpanzee, Cynomolgus and Rhesus.