Bisulfite sequence analysis of RASSF1A promoter methylation in one tissue pair of tumoral and normal tissue. RASSF1A promoter amplicons obtained from a single tumoral (T) and its paired normal (P) tissue sample were subcloned and each 50 clones analyzed by the use of bisulfite sequencing. For each clone the methylation status of analyzed CpG sites is shown (solid circles: methylation, open circles: no methylation). Numbers on x-axis refer to base pair positions as indicated in Figure 1. Asterisks indicate amplicons derived from densely methylated promoters demonstrating at least 11 methylated CpG sites.