NEUROBIOLOGY. For the article “Pregnenolone binds to microtubule-associated protein 2 and stimulates microtubule assembly” by Koichi Murakami, Arlette Fellous, Etienne-Emile Baulieu, and Paul Robel, which appeared in number 7, March 28, 2000, of Proc. Natl. Acad. Sci. USA (97, 3579–3584), the authors note the following correction. On page 3580, the paragraph “Competitive Binding Assay” should read “was incubated with 10 nM [³H]PREG” instead of “was incubated with 100 nM [³H]PREG.”