This article refers to:
RETRACTION
Volume 23, no. 22, p. 8161–8171, 2003, https://doi.org/10.1128/MCB.23.22.8161-8171.2003. After publication, this article was found to have problematic figures. Digital experts have informed us that some of the published data in this paper were very likely digitally manipulated. This represents a major deviation from established scientific standards for publications, and therefore we retract this paper. We apologize for these errors.