PTEN and central nervous system cancer: Other evidence has demonstrated that p27(Kip1) is a direct target for miRNAs 221 and 222, and may promote aggressive growth characteristics of glioblastomas [44], and miR-26a-mediated PTEN repression in a murine glioma model enhanced de novo tumor formation and indicates a new epigenetic mechanism for PTEN regulation in gliomas [45].