PTEN and glioblastoma: AMO-21 using T7-Exo can effectively deliver AMO to the rat brain via tail vein injection and reduce the level of miR-21 in glioblastoma, thereby inducing the expression of programmed cell death protein 4 (PDCD4) and phosphatase and tensin homologs (PTEN) in the tumor, reducing the volume of the tumor.