Cell Biology. The title of the article “Smad8 mediates the signaling of the receptor serine kinase” by Yan Chen, Anil Bhushan, and Wylie Vale, which appeared in number 24, November 25, 1997, of Proc. Natl. Acad. Sci. USA (94, 12938–12943), appeared incorrectly due to a printer’s error. The correct title is “Smad8 mediates the signaling of the ALK-2 receptor serine kinase.”