Tumor/background ratios in GBM/MT1-MMP+ tumors exhibited high values after 1 day (6.32±0.62, 5.77±0.77, 5.68±0.61 and 3.80±0.74 at 1, 2, 4 and 7 days p.i., respectively) in contrast to significantly lower values obtained with breast MT1-MMP- tumors (3.74±0.92, 4.02±0.75, 3.73±0.95 and 2.60±0.86 at 1, 2, 4 and 7 days p.i., respectively) (Fig 3B bottom panel). Here, MMP14 is linked to glioblastoma.