Sequence dependence of methylation-mediated repression. (A) Relative repression of methylated reporter plasmids in transient transfections of F9 cells. (B) Logarithmic graph of relative repression of methylated reporter plasmids in stable transfections of F9 cells. (C) Same as in B, except NIH3T3 cells were stably transfected. (D) Expression of unmethylated reporter plasmids normalized to unmethylated pCpGfree in stable transfections of F9 (empty) and 3T3 cells (gray). (A–D) Mean values and standard deviations for each graph were derived from three independent experiments and depict the ratio of expression from the unmethylated and methylated version of each plasmid. All means have P-values <0.05 when compared with unmethylated plasmids, except where indicated by asterisk. Methylated sequences are indicated next to the graphs. Sequences: ICR, Igf2/H19 imprinting control region; Lam, 2.3 kb lambda HindIII fragment; pBS, fragment of pBluescript; Igf2r, DMR2 from the Igf2r gene; pCpGfree, empty reporter plasmid.