In vivo ChIP-Seq for Bapx1 and Sox9 in the vertebral column of E12.5 embryos. (A) Targeting of the endogenous Bapx1 locus with a CBP- S peptide tag to generate N-terminal tagged BAPX1 protein. (B) The Bapx1 binding site motif enriched in the top 1000 binding sites from ChIP-Seq. (C) Whole genome binding site distribution for Bapx1 in the vertebral column of E12.5 wildtype embryos. The number on top of each peak represents the total number of peaks found at that distance from the TSS. Note that most peaks are found distally from the TSS. (D) GO annotation of the nearest genes to the peak shows enrichment of genes expressed in chondrocytes. (E) Similar binding site distribution for Sox9 and (F) GO annotation for the nearest genes showing enrichment of genes expressed in chondrocytes, x-axis is -log10 (p-value).