<prompt> True about DNA methylation -Alters gene expressionRole in carcinogenesisProtective mechanism against cleavage by restriction endonucleaseAll of these  <response>: DNA methylation alters the gene expression pattern in cells-for example it may cause X-chromosome inactivation, tumor suppressor gene silencing in cancer cells, suppresion of expression of repetitive elementsdeleterious elements viral genes that have been incorporated into genome of host over time.E. coli has 2 DNA methylation system, both using s-adenosyl methionine as methyl group donor.Adenine or cytosine methylation serve as a part of defence mechanism against cleavage by restriction endonuclease.Dam DNA adenine methylation mediates mismatch repair which improves overall fidelity of DNA replication. 