In MMTV-erbB2 transgenic mice, a model of HER2-positive breast cancer, in utero BPA exposure (500 ng/kg) daily between GD11-GD19 induces in offspring mammary tumorigenesis, earlier puberty onset, accumulation of terminal end buds (TEB), and prolonged estrus phase. This evidence concerns the gene ERBB2 and breast carcinoma.