PSEN2 and glioblastoma: It has several features including: (1) a survivin promoter for enhancing specific replication in tumor cells, since survivin is found to be overexpressed in glioblastoma, (2) a modified Ad5 protein through insertion of polylysine sequence (pk7), which binds to heparin sulfate proteoglycans also overexpressed in glioblastoma and (3) neural stem cells (NSCs) as its carrier, also contributing to selectivity.