BIOCHEMISTRY. For the article ‘‘Bioinorganic Chemistry Special Feature: An engineered two-iron superoxide reductase lacking the [Fe(SCys)4] site retains its catalytic properties in vitro and in vivo,’’ by Joseph P. Emerson, Diane E. Cabelli, and Donald M. Kurtz, Jr., which appeared in issue 7, April 1, 2003, of Proc. Natl. Acad. Sci. USA (100, 3802–3807; First Published March 13, 2003; 10.1073 pnas.0537177100), the authors note that they inadvertently labeled the time axis in Fig. 6 as hours instead of seconds. The corrected figure and its legend appear below. This correction does not affect the conclusions of the article. MEDICAL SCIENCES. For the article ‘‘Asialoerythropoietin is a nonerythropoietic cytokine with broad neuroprotective activity in vivo,’’ by Serhat Erbayraktar, Giovanni Grasso, Alessandra Sfacteria, Qiao-wen Xie, Thomas Coleman, Mads Kreilgaard, Lars Torup, Thomas Sager, Zubeyde Erbayraktar, Necati Gokmen, Osman Yilmaz, Pietro Ghezzi, Pia Villa, Maddalena Fratelli, Simona Casagrande, Marcel Leist, Lone Helboe, Jens Gerwein, Søren Christensen, Marie Aavang Geist, Lars Østergaard Pedersen, Carla Cerami-Hand, Jean-Paul Wuerth, Anthony Cerami, and Michael Brines, which appeared in issue 11, May 27, 2003, of Proc. Natl. Acad. Sci. USA (100, 6741–6746; First Published May 13, 2003; 10.1073 pnas.1031753100), the author name Jens Gerwein should have appeared as Jens Gerwien. The online version has been corrected. The corrected author line appears below.