For ChIP analysis, P19Cl6 cells and mouse embryos were cross-linked in 1% formaldehyde and chromatin was extracted and sonicated in microtubes using the Covaris® S2 instrument. Soluble chromatin was incubated with TBX1 antibody, H3K4me1 and H3K27Ac antibodies. For expression analysis, RNA was extracted from E9.5 embyos and P19Cl6 cells at day 1 during differentiation. For ChIP analysis, ChIP DNA or input samples were prepared for Solexa and Solid sequencing using Chip-Seq Sample Preparation kit and TruSeq SBS kit v3 HS or NEB Next DNA Simple Prep Master Mix set 3. For RNA-seq libraries preparation we used the Illumina's strand specific RNA seq protocol.