Abstract
The design of a mouse cross can affect the distribution of variation in the control and experimental groups. Often, the goal of a study involving mouse cancer models is to determine the effect of a gene or intervention of interest in different mouse groups without the confounding effects of strain background differences. The appropriate procedure for controlling genetic background will depend on the mouse model employed; two examples are provided here. The first example describes a simple model in which a single-mutant allele is followed in crosses on an inbred strain background. The second example describes a more complex cross in which the model is homozygous for a floxed allele of the gene of interest and carries a tissue-specific Cre transgene.