I got what I needed (<http://www.ncbi.nlm.nih.govjavascript:AL_get(this, 'jour', 'Proc Natl Acad Sci U S A.');>Proc Natl Acad Sci U S A. 2006 Aug 22;103(34):12903-10. Epub 2006 Aug 10). Many thanks to you all for your kind help. Marie Elias, MLS Medical Librarian The Medical Letter, Library 1000 Main Street New Rochelle, NY 10801 Tel: 914-235-0500 Ext. 307 or 334 Fax: 914-235-5079