Following the publication of this article, an interested reader drew to the Editor's attention that a pair of data panels in the cellular images shown in Fig. 1A on p. 2317 appeared to be overlapping, such that data which were intended to show the results from differently performed experiments had appparently been derived from the same original source. Moreover, in Fig. 1C and 5A, there appeared to be discrete splicing events for gel slices featured in these figure parts, and for the immunoblotting experiments shown in Fig. 2B, striking likenesses of certain of the bands appeared in different positions in different gels relative to each other where different experimental conditions were being shown, which seemed difficult to attribute purely to coincidence. After having conducted an internal investigation, the Editor of