NCI Dictionary of Cancer Terms
The NCI Dictionary of Cancer Terms features 7,800 terms related to cancer and medicine.
Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.
- listen (MEH-thuh-LAY-shun)
- A chemical reaction in which a small molecule called a methyl group is added to other molecules. Methylation of proteins or nucleic acids may affect how they act in the body.