FHIT and neoplasm: Interestingly, tumor suppressor genes, such as fragile histidine triad diadenosine triphosphatase (FHIT) and WW domain containing oxidoreductase (WWOX), are epigenetically-silenced (methylation-silenced) by promoter hypermethylation, and re-expressed as a consequence of their promoter CpG island demethylation, leading to cancer cell apoptosis, growth suppression, and inhibition of tumorigenicity [61].