Expression analysis of p15 andSDC4 by RT-PCR.

Complementary DNA was amplified by means of gene-specific primers and electrophoresed in 1.5% agarose gels; p15 mRNA was detectable in all the unmethylated samples but none of the methylated samples. Similar results were obtained for SDC4. The methylation status of each sample is shown above each lane. The integrity of RNA was verified by RT-PCR by means of primers specific for GAPDH. M is the marker lane. + indicates lanes where reverse transcriptase was added while − indicates lanes where reverse transcriptase was omitted (negative controls).