Concentration-dependent effect in wild-type (WT) and mtDNA-depleted (Rho) Hepa 1–6 mouse hepatoma cells of incubation with glycoursodeoxycholic acid (GUDCA) (A,D,G), glycochenodeoxycholic acid (GCDCA) (B,E,H) or paracetamol (C,F,I) for 48 h on Mdr1 (A,B,C), Mrp1 (D,E,F) and Mrp4 (G,H,I) expression as revealed by determining the abundance of mRNA using real-time quantitative RT-PCR. Values are expressed as mean ± SEM from five cultures measured in triplicate for each data point. *P < 0., significant differences between treated and untreated cells.