Indeed, in addition to the four proteins whose involvement in mammary carcinoma metastasis we report here, previous studies using various mammary carcinoma cell lines or tumor models had already implicated several other proteins in breast cancer progression (ANGPTL4, CTSB, IGFBP4, LOXL2) or invasiveness of breast tumor cells (ADAM9, ADAM10). The gene discussed is CTSB; the disease is breast neoplasm.