Supporting this model is a recently published study in which it was demonstrated that congenic rats that harbor, on the ACI genetic background, BN alleles across the Emca8 locus on rat chromosome 5 exhibited significantly reduced susceptibility to E2-induced mammary cancer that was accompanied by reduced expression in the mammary gland of Pgr, Wnt4 and Cd52 and increased expression of Spp1, relative to E2 treated ACI rats [24]. This evidence concerns the gene PGR and breast cancer.