Cover photograph (Copyright © 2002, American Society for Microbiology. All Rights Reserved.): Nuclear export of bulk mRNA is mediated by the heterodimeric export receptor NXF1/p15. Expression of a derivative of NXF1 (green-yellow) which no longer binds p15 restores mRNA export in Drosophila cells in which endogenous NXF1 is depleted (lower cell). In contrast, NXF1-depleted cells in which the exogenous NXF1 derivative is not expressed at detectable levels strongly accumulate bulk mRNA within the nucleus (top cell). This suggests that directional transport of mRNA cargoes across the nuclear pore complex can occur independently of p15. Bulk mRNA was visualized by in situ hybridization with an oligo(dT) probe (red). (See related article on p. 5405.)