Scholpp, S., Lohs, C. and Brand, M. Development130, 4881-4893.

An error in this article was not corrected before going to press.

Throughout the paper, efna4 should be read as EphA4, as the authors are referring to the gene encoding the ephrin A4 receptor (EphA4)and not to that encoding its ligand ephrin A4.

We apologise to the authors and readers for this mistake.