Glioblastoma is the most lethal brain tumor, partly because of its high intra-tumoral heterogeneity. There are four different glioblastoma subtypes (proneural, mesenchymal, classical and neural) based on their molecular profiles. Distinguishing between each of them is important for physicians in order to choose the appropriate clinical response. For example, proneural glioblastomas are more sensitive to chemotherapy than mesenchymal ones. Since the subtype profiling largely depends on transcriptome analysis, it is not financially practical to perform subtype profiling for every patient. The present study aims to develop a cheaper method to profile the glioblastoma subtypes. We treated patient-derived glioblastoma cell lines, which have been characterized based on the transcriptome, with different concentrations of polybrene, a cationic polymer commonly used to improve viral transduction efficacy. Cell growth was assessed by a luciferase-based cell viability assay. The toxicity of polybrene is dose-dependent and proneural glioblastoma cell lines are more sensitive to polybrene than mesenchymal ones. Since polybrene kills proneural glioblastomas, but not mesenchymal glioblastomas, at lower concentrations, it could potentially be used to distinguish among different glioblastoma subtypes.