Fig. 7. ß-Catenin and Lef1 physically interact with the Ihh promoter. (A) Schematic view of the 2.0 kb Ihh promoter region, showing the position of the three potential TCF/Lef1-binding sites relative to the translational start site (+1). (B) Chromatin immunoprecipitation for ß-catenin, H3-K4 tri-methylation and Lef1 from E13.5 dissociated wild-type humeri, showing immunoprecipitation of all three sites in the Ihh promoter, but none of the tubulin promoter. Real-time PCR quantification (normalized to input and indicated by the numbers below) revealed that site 1 is bound with the highest affinity and site 3 with the lowest (n=3).