The aim of this research was to develop a methodology for the diagnosis of a brain tumor by finding the interrelationships between MMP-1, UCH-L1, and the 20S proteasome, and by examining the influence of the degree of the glioblastoma, the patient’s age, and the tumor size on the amount of the measured proteins in the blood plasma. This evidence concerns the gene UCHL1 and glioblastoma.