Physiology. In the article “Inositol 1,4,5-tris-phosphate activation of inositol tris-phosphate receptor Ca²⁺ channel by ligand tuning of Ca²⁺ inhibition” by Don-On Daniel Mak, Sean McBride, and J. Kevin Foskett, which appeared in number 26, December 22, 1998, of Proc. Natl. Acad. Sci. USA (95, 15821–15825), due to printer’s errors, the following corrections should be noted. The title of the article should read “Inositol 1,4,5-trisphosphate activation of inositol trisphosphate receptor Ca²⁺ channel by ligand tuning of Ca²⁺ inhibition.” On page 15821, the first line of the abstract should read “Inositol 1,4,5-trisphosphate (IP₃)” instead of “Inositol 1,4,5-tris-phosphate (IP₃),” and on page 15821, in the right column, the first line of the abbreviations footnote should read “IP₃, inositol 1,4,5-trisphosphate” instead of “IP₃, inositol 1,4,5-tris-phosphate.”