Biochemistry. In the article “Cloning and characterization of four murine homeobox genes” by Alessandra Cecilia Rovescalli, Sadamitsu Asoh, and Marshall Nirenberg, which appeared in number 20, October 1, 1996, of Proc. Natl. Acad. Sci. USA (93, 10691–10696), the following should be noted: The Genbank accession numbers for Uncx-4.1, OG-2, OG-9, OG-12, OG-12a, and OG-12b were incorrect in the footnotes to the article. The correct order is as follows: Uncx-4.1: U65069, U65070; OG-2: U65067; OG-9: U65068; OG-12: U65071, U65072; OG-12a: U66918; and OG-12b: U67055U67055.