Fig. 5.
Methylation-specific PCR of exon 1a of the p16Ink4a gene. One to 2 µg of normal mouse DNA purchased from Clontech (CONT) and tumor cell DNA (TUM) were modified by treatment with bisulfite and subjected to PCR with primers specific for either methylated (M primers) or unmethylated (U primers) CpG residues. CONT DNA exhibited a PCR product only with primers specific for unmethylated DNA while the tumor cell DNA only yielded a PCR product with the primers specific for methylated DNA. The lanes marked PC were procedure controls that lacked any added DNA and were taken through all of the experimental steps; lanes marked NEG were negative buffer controls for the PCR reaction and also lacked any added DNA template. Similar results were observed in DNA derived from wild-type tumors.