Nat. Biotechnol. 21, 936–940 (2003)

Enanta Pharmaceuticals was mistakenly omitted from the affiliation listing in this article. The affiliations should have read as follows:

Sylvie Vincent1,2, Abraham Thomas1, Bradley Brasher1,2 & John D Benson1,2

1Enanta Pharmaceuticals, 500 Arsenal Street, Watertown, Massachusetts 02472, USA. 2Present addresses: GenPath Pharmaceuticals, 300 Technology Square, Cambridge, Massachusetts 02139, USA (S.V.); SelectX Pharmaceuticals, 44 Hartwell Avenue, Lexington, Massachusetts 02421, USA (B.B.); Novartis Institutes for Biomedical Research, 100 Technology Square, Cambridge, Massachusetts 02139, USA (J.B.). Correspondence should be addressed to J.B. (john.benson@pharma.novartis.com).