In order to investigate the impact of signalling proteins on the phenotype and malignant behavior of glioblastoma cells, we optimized the transfection procedure of human glioblastoma cell lines U251, U373, GaMG and of primary cells obtained from a patient's tumor using nucleofection technology in conjunction with plasmid pmaxGFP. We describe the optimization procedure, show that a high percentage of the cells can be transfected and that nucleofection does not cause phenotypic alterations of the cells. Therefore, we conclude that nucleofection is a highly efficient tool to deliver plasmids for transient protein overexpression and siRNA for specific protein knock-down to different glioblastoma cell lines or primary cells.