DNMT1 and colorectal adenoma: Results obtained in mouse models again reflect the need for well-adjusted DNMT function to maintain cellular homeostasis: DNMT1 knockout mice are ‘protected’ against the development of colorectal adenomas when crossed with APC-deficient mice (Laird et al, 1995), but they are ‘prone’ to develop lymphomas in the context of mice susceptible to this type of neoplasia (Eden et al, 2003).