Nat. Protoc. 7, 1024–1041 (2012); published online 3 May 2012; corrected after print 24 February 2016

In the version of this article initially published, the units for the concentration of NaCl in the NST buffer described in the Reagent Setup section were incorrect. The correct unit should be mM. The error has been corrected in the HTML and PDF versions of the article.