MPST and astrocytoma (excluding glioblastoma): More recently, a role for H2S has also been hypothesized in glioblastoma multiforme (GBM) and neuroblastoma in light of the finding that the expression and activity of CBS, gamma-cystathionase (CTH, EC 4.4.1.1), and 3-mercaptopyruvate sulfurtransferase (MPST, EC 2.8.1.2) were found in the human glioblastoma-astrocytoma (U-87 MG) and neuroblastoma (SHSY5Y) cell lines [6].