A comparative analysis between sequences of Msx1 promoter gene from human, mouse, and fugu allowed us to identify sequences highly conserved among these animals. One of the regions of great homology is localized between the positions -4622 and -4572, including the region described as distal enhancer. In this region putative transcription factors binding sites for Nkx2.5, CTF-CBP, Bicoid, Brn2, and Oct were found. To evaluate the functionality of these sites we performed EMSA analysis using two different regions from the distal enhancer and nuclear protein extracts from embryos. The results showed that in the presence of a Bicoid consensus binding site a DNA-protein complex can be formed. The identification of the proteins involved in this complex by mass spectrometry and Western blotting identified OTX2, a Bicoid-like protein. This protein was shown to be present in nuclear extracts of the embryonic stages analyzed by Western blot. Altogether these results suggest that OTX2 is a putative candidate to activate mice Msx1 gene from distal enhancer. (C) 2007 Elsevier Inc. All rights reserved.