Source:http://linkedlifedata.com/resource/umls/id/C1158483
GO: The addition of alkyl groups to many positions on all four bases of DNA. Alkylating agents can also modify the bases of incoming nucleotides in the course of DNA synthesis. [ISBN:0716735970],NCI: DNA Alkylation involves the addition of alkyl groups to any of several vulnerable positions on all four of the DNA bases. Alkylating agents can also modify the bases of incoming nucleotides in the course of DNA synthesis. (Gene Ontology and NCI)