Enhancers are enriched by histone H3 lysine 4 mono methylation (H3K4me1). To gain insight into the relation between enhancers and developmental state, chromatin immunoprecipitation coupled with massive parallel sequencing (ChIP-seq) was performed in several cell types to determine the genome-wide binding targets of H3K4me1 and several other possible enhancer associated modifications. DNA was enriched by chromatin immunoprecipitation (ChIP) and analyzed by Solexa sequencing. A chromatin IP against histone H3 or whole cell extract was sequenced and used as the background to determine enrichment. ChIP was performed mainly using antibodies against the chromatin marks H3K4me1 and H3K27ac.