4.2. (D)-2-Hydroxyglutarate Measurements

(D)-2-hydroxyglutarate levels were measured in the cell culture supernatant of IDH1^mut GSCs as decribed by Balss et al. [36]. In brief (d)-2-hydroxyglutarate dehydrogenase (HGDH) catalyzes the reduction of NAD+ to NADH by oxidation of (d)-2-hydroxyglutarate to α-ketoglutarate. NADH is then detected by a diaphorase/resazurin system which in turn can be measured by the fluorescent product resorufin which is exited at 540 nm and detected at 610 nm.