Figure 1.

Analysis of IGF2 alterations. (A) Examples of the methylation status of CTCF6 analysed by a combined bisulphite restriction assay (COBRA). Bisulphite-modified PCR products were digested with MluI. Upper and lower lanes indicate unmethylated and methylated fragments, respectively. Numbers above lanes indicate the tumour number. Numbers below lanes show the percentage of methylated DNA fragments containing CTCF6. The mean value of the DNA methylation percentages calculated from three COBRA experiments is shown in Table 1. Methyl., control methylated DNA. The IGF2 status is shown above the tumour numbers. LOI, loss of IGF2 imprinting; LOH, loss of heterozygosity in the IGF2 region; ROI, retention of IGF2 imprinting. (B) Electrophoretic pattern of genomic DNA PCR products or RT–PCR products after AvaII digestion. Reverse transcriptase–PCR analysis shows LOI in two tumours and ROI in three tumours.