MMP9 and glioblastoma: In the CGGA and TCGA databases, Piezo1 expression was positively correlated with the genes TIMP1, MMP2, MMP9, MAPK13, MAPKAPK2, PIK3R6, PIK3CD, PLOD1, and AKT2, and was also positively correlated with the genes TIMP1, MMP2, MMP9, MAPK13, MAPKAPK2, PIK3R6, PIK3CD, PLOD1, and AKT2, as opposed to low-grade glioblastomas (WHO classification II and WHO classification III) in glioblastomas (WHO grade IV) had significantly higher expression of all ECM-related genes positively associated with Piezo1.