Hypermethylation of the RASSF1 promoter respon- sible for RASSF1A expression has a well-established role in tumor progression in several organ systems and tissue types [26,40-45], including several endo- crine tumors.
Epigenetic suppression of RASSF1A expression in papillary thyroid carcinoma has been strongly implicated in early tumor forma- tion [31,32,46,47].