Nat. Protoc. 6, 1183–1191 (2011); doi:10.1038/nprot.2011.361; published online 21 July 2011; corrected after print 17 December 2014 In the version of this article initially published, there was some confusion over the interpretation of the sentence “Further, defeats should be run under constant veterinary evaluation and with full approval of all necessary institutional review boards and standards.