Sánchez Alvarado A. 2013. Learning about loss. eLife 2:e00533. doi: 10.7554/eLife.00533. Published 10 September 2013
An error was introduced into the fourth paragraph of this article by eLife editorial. The third sentence of this paragraph originally referred to activin-1 where it should have referred to activin-2.
The article has been corrected accordingly.