BIOCHEMISTRY. For the article “Bepridil opens the regulatory N-terminal lobe of cardiac troponin C” by Yu Li, Michael L. Love, John A. Putkey, and Carolyn Cohen, which appeared in number 10, May 9, 2000, of Proc. Natl. Acad. Sci. USA (97, 5140–5145), the authors note the following correction to the Acknowledgments. “We thank the staff at the Cornell High Energy Synchrotron Source for assistance with data collection.”