Anaplastic lymphoma kinase (ALK, anaplastic lymphoma kinase) is a receptor type tyrosine kinase, and is found to be expressed in the central and peripheral nervous system at late embryonic stage. Motegi et al. developed an agonist monoclonal antibody against the extracellular domain of ALK. This monoclonal antibody (clone mAb16-39) elicits tyrosine phosphorylation of ALK in human neuroblastoma (SK-N-SH) cells. And it also induces further phosphorylation of signal transfer molecules like IRD-1 (insulin receptor substrate-1) which interact with ALK. Moreover, continuous incubation with this antibody induced the cell-growth and neurite outgrowth of SK-N-SH cells (ref. 1).