Examination of the levels of secreted proteins in conditioned medium from these cultures revealed that TRAF2 overexpression in osteotropic cells is associated with elevated levels of various pro-tumour and pro-migratory factors including uPAR, VEGF, IL-1, TSP-1 and Serpine 1, each with functions that enable primary and metastatic breast cancer cells to spread (Table S1). This evidence concerns the gene PLAUR and breast carcinoma.