In view of the important roles of the INSR and IGF1R signaling pathways in breast cancer, we investigated the subcellular distribution of both receptors, as well as that of members of the extracellular signal-regulated kinases (ERK) and protein kinase B/AKT (PKB/AKT) families, two prototypical networks of cytoplasmic molecules involved in insulin/IGF1 signaling. This evidence concerns the gene INSR and breast carcinoma.