A binding partner for an orphan receptor

Cell Biology Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase that is important during the development of the nervous system. ALK can also be aberrantly activated in certain types of cancers, including neuroblastoma and lung adenocarcinoma. Until now, ALK was an “orphan” receptor because its ligand was not known. Now, Murray et al. show that heparin binds directly to ALK and stimulates its activity (see the Focus by Lemke). An antibody that blocked the binding prevented heparin from activating this receptor tyrosine kinase, providing a potential avenue for therapeutic intervention. Sci. Signal. 8 , ra6; see also fs2 (2015).