PAX3 and neoplasm: To gain insight into the epigenetic regulation of the Pax3:Foxo1 locus, we examined active (H3K4me3 and H3K9Ac) and repressive (H3K27me3 and H3K9me3) histone modification marks by chromatin immunoprecipitation (ChIP) in tumor cells representing both Pax7CreER (U29415 and U31425) and Myf6Cre (U23674 and U21459) lineages of origin.