Our research has been focused on the pathways that regulate mammary gland involution after the pregnancy/ lactation cycle and how these pathways become deregulated in breast cancer. Over the past years, our group has unveiled the role of calpains, calcium-dependent proteases, in the mammary tissue. We have demonstrated a dual role for calpains during involution, controlling programmed cell death of epithelial cells and adipocyte redifferentiation. Moreover, in breast cancer cell lines, calpains are involved in adhesion and cell migration. In the near future we will try to eluciate new functionsa of these proteases according to their subcellular localization.