The addition of ERα over-expression to cyclin D1 over-expression in the CERM/D1 mice significantly increased the percentage of mice demonstrating one or more HANs at one year of age (Fisher’s exact, one tailed test, p≤0.05); however, it did not increase the number of mice developing mammary adenocarcinoma (Figure 1A). Here, ESR1 is linked to breast adenocarcinoma.