Enrichment of H3K4me3 and H3K27me3 with respect to developmental expression status. The two histone modifications H3K4me3 and H3K27me3 are shown to be important for the developmental regulation of imprinted genes. Using Mikkensen et al.  as a source for histone modification enrichment and expression data, histone modification profiles of H3K4me3 and H3K27me3 at imprinted gene transcription start sites were assessed in mouse (A) embryonic stem cells (ESCs), (B) neural progenitor cells (NPCs) and (C) mouse embryonic fibroblasts (MEFs) at developmentally expressed and repressed imprinted genes. Though a trend is observed, profiles at developmentally expressed imprinted genes do not differ significantly to repressed genes for ESCs or MEFs (chi-square contingency test, ESC:P = 0.097, MEF: P = 0.079). NPC data does not meet the conditions required for the chi-square contingency test.