Nat. Protoc. 10, 941–958 (2015); doi:10.1038/nprot.2015.057; published online 4 June 2015; corrected after print 5 August 2015

In the version of this article initially published, the concentration of ROCK inhibitor Y27362 in Step 2 was incorrectly given as 10 mM. The correct concentration to be used is 10 μM. The error has been corrected in the HTML and PDF versions of the article.