*2.9. Immunohistochemistry*

Immunohistochemistry analysis was performed in five μm-thick frozen or formalin-fixed paraffin-embedded liver tissue sections using antibodies against CYP3A (Biotrend, Cologne, Germany), CYP1A, CYP2C (a gift from Dr. R. Wolf, Biochemical Research Centre, University of Dundee, Dundee, UK), CYP2E1, Arginase1 (Sigma-Aldrich Corp., St. Louis, MO, USA), GS (BD Bioscience, Heidelberg, Germany), and CPS1 (Abcam, Cambridge, UK) (Table 1). The following horseradish peroxidase-conjugated secondary antibodies were used: anti-rabbit IgG (Agilent, Santa Clara, CA, USA), anti-mouse IgG (Sigma-Aldrich Corp., St. Louis, MO, USA), and anti-rat IgG (Linaris GmbH, Heidelberg, Germany) (Table 1). In order to visualize the target signal, the tissues were stained with either 3,3 -diaminobenzidine solution (Vector Laboratories, Peterborough, UK) or AEC+ high sensitivity substrate chromogen (Agilent, Santa Clara, CA, USA). The nuclei were visualized by counter-staining with Mayer's haematoxylin.


**Table 1.** Antibodies and staining conditions.
