MEDICAL SCIENCES. For the article ‘‘A phase I clinical trial with monoclonal antibody ch806 targeting transitional state and mutant epidermal growth factor receptors,’’ by Andrew M. Scott, Fook-Thean Lee, Niall Tebbutt, Rebecca Herbertson, Sanjeev S. Gill, Zhanqi Liu, Effie Skrinos, Carmel Murone, Timothy H. Saunder, Bridget Chappell, Anthony T. Papenfuss, Aurora M. T. Poon, Wendie Hopkins, Fiona E. Smyth, Duncan MacGregor, Lawrence M. Cher, Achim A. Jungbluth, Martin W. Brechbiel, Roger Murphy, Antony W. Burgess, Eric W. Hoffman, Terrance G. Johns, and Lloyd J. Old, which appeared in issue 10, March 6, 2007, of Proc Natl Acad Sci USA (104:4071– 4076; first published February 28, 2007; 10.1073 pnas.0611693104), the authors request that Gerd Ritter be added to the author list, between Achim A. Jungbluth and Martin W. Brechbiel, and be credited with contributing new reagents/ analytic tools. The online version has been corrected. The corrected author and affiliation lines, author contributions, and related footnote appear below.