MMP1 and glioblastoma: Overexpression of MMP-1 on the basis of AGBL4 knockdown could counteract the inhibitory effect of AGBL4-decrease on GBM cells, which was manifested as the improvement of the proliferation capacity of AGBL4-knockdown U87-MG and A172 cells after complementing MMP-1 in CCK-8 assay (Figures 6C, D).