AREG and neoplasm: Expression of Esr1, Pr and downstream target genes of both receptors: amphiregulin (Areg), receptor activator of nuclear factor kappa-B ligand (Rankl), and wingless-type MMTV integration site family, member 4 (Wnt4) were also unchanged in non-tumor bearing mammary glands of MARKO mice compared to controls (Fig. S2).