RASSF1 and neoplasm: All other neuroblastoma tumours (64 of 68; 94%) showed methylated RASSF1A. Hypermethylation in tumours was observed very frequently in all of the stages of neuroblastoma examined, including stage 1, 2 and 4S tumours (Supplementary Table) and no correlation between RASSF1A methylation and known prognostic factors including stage, age and MYCN amplification was detected.