AKT1 and glioblastoma: Lentiviruses expressing oncogenes such as HRAS or AKT were efficiently introduced into mice expressing Cre-recombinase under varying promoters such as GFAP. Glioblastoma tumors were efficiently formed when lentiviruses harboring activated RAS and AKT were injected into mice expressing GFAP-Cre on a Trp53 heterozygous background [22, 23].