Nat. Protoc. 9, 2586–2606 (2014); doi:10.1038/nprot.2014.170; corrected online 22 October 2014

In the version of this article initially published online, the sequence for the MWS21 oligonucleotide was incorrectly listed in Table 3 as 5‘-CCAGCAGAAGACGGCATACGAGATXXXXXXGTGACTGGAGTTCAGACGTGTGC-3’. The second nucleotide in the sequence should be A, not C, and the correct sequence is 5‘-CAAGCAGAAGACGGCATACGAGATXXXXXXGTGACTGGAGTTCAGACGTGTGC-3’. The error has been corrected in the PDF and HTML versions of this article.