Biochemistry. In the article “A protein encoded by a group I intron in Aspergillus nidulans directly assists RNA splicing and is a DNA endonuclease” by Yugong Ho, Sea-Jin Kim, and Richard B. Waring, which appeared in number 17, August 19, 1997, of Proc. Natl. Acad. Sci. USA (94, 8994–8999), The authors request that the following change be noted. In Fig. 2A, the 3 min timepoint lane headings should all read 1 min; Fig. 2B is correct.