Neural cell adhesion molecule (NCAM), also called CD56, is a homophilic-binding glycoprotein expressed on the surface of neurones, glia and skeletal muscle that has been implicated as having a role in cell–cell adhesion.97 NCAM expression was investigated in 16 NFPAs, eight somatotrophinomas and five normal pituitaries, and no significant difference of NCAM expression was observed either between PT and normal pituitary or NFPA and somatotrophinoma.42 There was also no association between NCAM expression and invasion.42 The gene discussed is NCAM1; the disease is growth hormone-producing pituitary gland adenoma.