A systems-level approach to parental genomic imprinting: the imprinted gene network includes extracellular matrix genes and regulates cell cycle exit and differentiation

Methylation pattern of differentially methylated regions at IG loci. Bisulfite-treated genomic DNAs from BJ1 and JB6 MEFs grown in vitro for the indicated period of time were PCR amplified at the indicated loci (A, H19; B, Igf2r; C, Dlk1-Meg3; D, Mest), subcloned, and sequenced. Filled and open circles denote methylated and unmethylated CpGs, respectively. Yellow circles denote variation from the corresponding C57BL/6J reference genome. B6 and JF1 indicate the parental allele from which each cloned amplicon is derived. Panels on the right side of the figure display the percentage of methylated maternal or paternal allele at each locus and each time point.