Considering Nr2f1 as the main target of the Mcs1a locus, we also looked at its transcript levels in mammary glands (MG), rat mammary epithelial cells (RMECs) and mammary carcinomas (carc.; induced by DMBA and MNU) from susceptible congenic control (WF.Cop) and Mcs1a resistant congenic rats. This evidence concerns the gene NR2F1 and breast carcinoma.