Down-regulation of PEBP1, also known as the Raf-1 kinase inhibitor protein (RKIP), is associated with glioma progression [80,81], and it has been demonstrated that RKIP, by inhibiting MMP-2 and MMP-9 expression, markedly reduces the ability of glioma cells to migrate and invade [82]. Here, MMP2 is linked to central nervous system cancer.