Based on reports of the binding of three SIBLINGs to, and activation of, specific MMPs (BSP/MMP-2, OPN/MMP-3, DMP1/MMP-9) in biochemical and biologic systems [22–24], we hypothesized that the three SIBLINGs with cognate MMP partners (BSP-MMP2, OPN-MMP3, DMP1-MMP9) also colocalize, and potentially interact, in prostate neoplasms. This evidence concerns the gene IBSP and prostate neoplasm.