Figure 2: Biosynthesis of active Cbl species is GSH-dependent. (a) 24 hr treatment of NAC (100 mM), an acetylated derivative of cysteine, increased levels of active Cbl species AdoCbl and MeCbl and levels of CNCbl and GSCbl, while the level of OHCbl was decreased, . (b) Four hr treatment with the GSH synthesis inhibitor BSO (1 mM) decreased levels of GSCbl, AdoCbl, and MeCbl, while it increased the level of OHCbl, . All data represent the mean ± SEM and Cbl levels were normalized against control values. (c) 24 hr treatment of NAC (100 mM) increased the GSH level, . (d) Four hr treatment of BSO (1 mM) decreased the GSH level, . Asterisks () indicate a significant difference () from control group.