were performed, resulting in production of high-quality DNA for labeling reactions and microarray hybridization. (TIF) Figure S2 Primary hepatocytes isolated from C57BL/6J mice. Primary hepatocytes were obtained by perfusion of the livers of C57BL/6J mice with collagenase type IV. (A) Photomi- crograph of a monolayer of the isolated primary mouse hepatocytes (magnification, 640). (B) mRNA levels of the typical hepatocyte markers albumin and transferrin assessed by RT-PCR analysis. (TIF) Figure S3 Chromosomal distribution of H3K9me3 and H3K4me3 targets. Each dot indicates the mean log2 value of signals in the H3K9- or H3K4-trimethylated region of their corresponding gene. (TIF) References 1. Jenuwein T, Allis CD (2001) Translating the histone code. Science 293: 1074– 1080. 2. Strahl BD, Allis CD (2000) The language of covalent histone modifications. Nature 403: 41–45. 3. Margueron R, Trojer P, Reinberg D (2005) The key to development: interpreting the histone code? 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