Dysfunctional levels of PTEN have been reported in the 50-80% of endometrial carcinoma, glioblastoma and prostate cancer, and in 30-50% of breast, colon and lung tumors, while germline mutations of PTEN have been described in a group of autosomal dominant syndromes collectively referred to as the PTEN hamartoma tumor syndromes (PHTS) [8]. This evidence concerns the gene PTEN and glioblastoma.