In our experiments we administered intra-peritoneal carcinogen at twice and in both studies the rats received metoclopramide daily, as inductor of PRL release and, as has been demonstrated PRL acts as positive growth factor in mammary tumour development suggesting that the hormonal mileu around the time of carcinogen exposure affects not only the incidence and phenotype of mammary transformants but also the molecular events associated with mammary carcinogenesis [3,7,25]. Here, PRL is linked to breast cancer.