S100A4 and breast carcinoma: As positive staining for S100A4 occurs more often in advanced rather than in early breast cancers in contrast to the other three MIPs (de Silva Rudland et al, 2011; Winstanley and Rudland, 2013), it may be that only S100A4 has a role in the subsequent progression of those patients with BMs, whereas the other three MIPs stimulate earlier and different steps in the metastatic pathways.