Glioblastomas are the most aggressive and the most invasive tumors of central nervous system, and are classified as grade IV astrocytoma by the criteria of the World Health Organization. They can develop either de novo or from a lower-grade astrocytoma, and each type has its own characteristics genetic changes. There are specific signalling pathways involved in disease development, among which is Wnt pathway. Wnt pathway is important during normal embryonic development, differentiation and apoptosis, and its disrupted functioning is involved in tumor development. Protein Dishevelled1 (DVL1) is cytoplasmatic phosphoprotein, it comes first in downstream cascade from receptor Frizzled (Fz) and it is one of the crucial molecules of Wnt signalling pathway. When Wnt pathway is activated, signal is transmitted by the interaction of Fz with DVL1 which then inhibits activity of degradation complex. It results in β-catenin entering the nucleus and by transcription of target genes. If the signalization mediated by DVL1 is disrupted, it results in tumor development and progression. We believe that genetic changes of in DVL1 gene are involved in occurrence of glioblastomas, so the goal of this research is to optimize the conditions of the Polymerase Chain Reaction (PCR) for amplification of microsatellite markers of DVL1 gene. In those optimized conditions, very specific markers will be amplified and they will be used for microsatellite instability and loss of heterozygosity analyses of DVL1 gene. Results of this research will contribute to more succesfull and more specific amplification of microsatellite markers fo DVL1 gene.