Boxplot showing RASSF1A and DOK1 promoter methylation levels in non-cirrhotic, cirrhotic, and HCC tissues.

Methylation levels were measured by pyrosequencing at different CpG sites and expressed as the mean percentage of all CpGs analyzed at a given gene. The statistical significance for DNA methylation level in non-cirrhotic and cirrhotic tissues was calculated by comparison to HCC samples.