The level of miR-21 was up-regulated in the tissue of higher grade gliomas (grade III and glioblastomas) compared with that of the non-neoplastic brain tissues and promote cell survival and invasion in glioblastoma cells [11, 12] A range of target genes have been identified for miR-21, among which, PTEN [13], RECK4 [12], PDCD4 [14] have been shown to closely related to the functionality of miR-21 in growth and metastasis of gliomas. The gene discussed is PDCD4; the disease is glioblastoma.