Localization of Pbx1 transcripts in developing rat embryos.

Recently, a new family of homeodomain proteins has emerged, that includes extradenticle, ceh-20, Pbx1, Pbx2 and Pbx3. The Pbx family has been shown to modulate the biological activities of the Hox proteins. We demonstrate here by in situ hybridization that Pbx1 transcripts are present in many embryonic tissues. Highest levels of Pbx1 expression in the developing embryo, from 12 to 20 days post coitum, are found in neuronal tissues, including brain, spinal cord and ganglia. In addition, Pbx1 transcripts are also detectable in the gut, lung, olfactory epithelium and kidney. The expression pattern of Pbx1 overlaps with that of many of the Hox gene products and is consistent with them acting in parallel to regulate common target genes.