PTEN and central nervous system cancer: We identified several genes which have previously been described in glioblastoma (GBM) and lower grade (WHO grade II and grade III) gliomas such as PTEN, NF1 and IDH1 and concentrated our efforts on a gene not previously implicated to have copy number loss, LOH or mutations in GBMs or low grade gliomas namely, Zinc Finger E-Box Binding Homeobox 1 gene (ZEB1).