Spatially and temporally restricted expression of Hox genes requires multiple mechanisms at both the transcriptional and the post-transcriptional levels. New insight into this precise expression mechanism comes from recent findings of a novel sense–antisense miRNA combination from the bithorax complex of Drosophila melanogaster.1-4 These two miRNAs encoded from the same locus target 3′ untranslated regions of anterior hox genes, Antp, Ubx and abd-A to establish the dominance of posterior hox gene Abd-B in its expression domain. Such double-edge tools, sense–antisense miRNA (...) combinations, also operate at multiple loci in the genome implicating their wider impact on the post-transcriptional gene regulation in eukaryotes. BioEssays 30:1058–1061, 2008. © 2008 Wiley Periodicals, Inc. (shrink)