The objective of the present study was to investigate l-cysteine desulfuration (Scheme 1) in various regions of human brain and in human gliomas of various grades of malignancy, through the estimation of the activity of enzymes participating in the formation and metabolism of sulfane sulfur compounds, i.e., cystathionine γ-lyase (CTH, EC 4.4.1.1), 3-mercaptopyruvate sulfurtransferase (MPST, EC 2.8.1.2), rhodanese (thiosulfate sulfurtransferase, EC 2.8.1.1), and through the determination of the level of sulfane sulfur, cysteine, glutathione and cystathionine. This evidence concerns the gene TST and central nervous system cancer.