This MAb reacts with an extracellular domain (close to the transmembrane) of CD56/NCAM. Three isoforms of neural cell adhesion molecule (NCAM) are produced by differential splicing of the RNA transcript from a single gene. The 135kDa isoform is the basic molecule, which is glycosylated or sialylated to produce the mature species. Anti-CD56 recognizes two proteins of the neural cell adhesion molecule, the basic molecule expressed on most neuroectodermally derived tissues and neoplasms (e.g. retinoblastoma, medulloblastomas, astrocytomas, neuroblastomas, and small cell carcinomas). It is also expressed in some mesodermally derived tumors (rhabdomyosarcoma). Anti-CD56 plays an important role in the diagnosis of nodal and nasal NK/T-cell lymphomas.