Promoter hypermethylation has been described for tumor suppressor genes including CDKN2A, RASSF1, RB1, DUSP2, and MGMT (180–184), although protein expression studies have not shown that these genes are consistently silenced in MCC tumors (53, 164, 182, 184, 185). This evidence concerns the gene RB1 and Merkel cell skin cancer.