KLK6 and melanoma: To obtain murine models of the common brain metastatic signature observed in patients with these three cancer types, <i>in vivo</i> experiments were performed after intracardiac injections of cancer cell lines.<h4>Results</h4>Among patients, we identified 23 common genes up-regulated in brain metastases from breast cancer, melanoma, and lymphoma, including KLK6, a serine protease with trypsin-like properties and physiological expression in oligodendrocytes and normal brain endothelial cells.