Hepatic expression of genes involved in glutathione synthesis. Hepatic expression of GCS-LS (a), GCS-HS (b), GS (c) mRNA after GalN administration. The level of mRNA is expressed as the expression level relative to the average for the control group at 0 h. Results are mean ± SEM. Time course of control and proline groups are denoted by solid line and dotted line, respectively. A significant difference between the two groups is denoted by “asterisk” (**P < 0.01).