ADO and glioblastoma: We further demonstrated that hypotaurine to be one of the top-ranked metabolites for differentiating glioblastomas (GBMs) from low-grade gliomas and that there was also a strong association between the intratumoral hypotaurine levels and the expression levels of its biosynthetic enzyme cysteamine (2-aminoethanethiol) dioxygenase (ADO)17.