Figure 2.

Methylation analysis of the PTEN CpG island using COBRA. Two regions of the PTEN CpG island were investigated for methylation using COBRA and were designated regions 1 and 3 as indicated in Figure 1. A, Region 1 was assayed for methylation using the restriction endonuclease AatII. Identical results were also obtained using the restriction endonuclease ClaI. B, Region 3 was assayed for methylation using the restriction endonuclease TaqI. Identical results were also obtained using the restriction endonuclease MluI. No methylation was found in any sample tested. For each region we used M.SssI in vitro methylated normal blood DNA as a positive (+ve) control. -, undigested PCR product; +, digested PCR product.