Source:http://linkedlifedata.com/resource/umls/id/C0598935
NCI: A process in which normal cells are changed so that they are able to form tumors. Substances that cause cancer can be tumor initiators.,NCI: The first stage of tumor induction by a carcinogen, consisting of subtle alteration of cells by exposure to a carcinogenic agent so that they are likely to form a tumor upon subsequent exposure to a promoting agent. (NCI)