ανβ3-OPN interaction promotes cancer cell migration and invasion in prostate and breast cancer as well as in chondrosarcoma where OPN-ανβ3 binding leads to MMP-9 up-regulation through the FAK/MEK/ERK/NF-Κβ pathway [37,38,39,40] (Figure 1E). This evidence concerns the gene SPP1 and breast carcinoma.