Myelin under construction—teamwork required

Myelinating glial cells synthesize specialized myelin proteins and deposit them in the growing myelin sheath that enwraps axons multiple times. How do axons and myelinating glial cells coordinate this spectacular cell–cell interaction? In this issue, Trajkovic et al. (p. 937) show that neuronal signaling regulates cell surface expression of the myelin proteolipid protein in cultured oligodendrocytes in unexpected ways that may also contribute to myelination in situ.