Suppression of Gmnn expression by siRNA in cells derived from a variety of carcinomas, adenocarcinomas, glioblastomas, and osteosarcomas induces DNA re-replication, DNA damage, a DNA damage response, and finally apoptosis (Melixetian et al., 2004; Zhu et al., 2004; Tachibana et al., 2005; Zhu and Dutta, 2006), whereas under the same conditions, suppression of Geminin in cells derived from normal human tissues does not prevent their continued proliferation (Zhu and Depamphilis, 2009). Here, GMNN is linked to glioblastoma.