Fig 1: Effects of omeprazole and lansoprazole enantiomers on CYP1A1 mRNA, protein and EROD activity in primary human hepatocytes. Panel A and Panel B: RT-PCR analyses of CYP1A1 and CYP1A2 mRNA and western blots of CYP1A1 and CYP1A2 from two different cultures (HH52 and Hep220770) are shown. Human hepatocytes were incubated for 24 h (mRNA analysis) or 48 (protein analysis) with S-OME, R-OME, rac-OME, S-LAN, R-LAN, rac-LAN, TCDD and vehicle (DMSO; 0.1% v/v). RT-PCR data are the mean ± SD from triplicate measurements and are expressed as fold induction over vehicle-treated cells. Data were normalized to GAPDH mRNA levels. Density of bands in western blots was quantified by densitometry and the values are indicated along with respective blots. Panel C: EROD and cytotoxicity: Human hepatocytes (culture Hep220774) were treated for 24 h with S-OME, R-OME, rac-OME, S-LAN, R-LAN, rac-LAN, TCDD and vehicle (DMSO; 0.1% v/v). Upper bar graph: An activity of 7-ethoxyresorufin- O-deethylase (EROD) was measured by fluorescent spectrophotometry with 530 nm excitation and 590 nm emission filters. Treatments were performed in triplicates. The data are expressed as fold induction over the value from control cells. Lower bar graph: A conventional MTT test was performed and absorbance was measured at 540 nm. Treatments were performed in triplicates. The data are expressed as percentage of viability of control cells. An asterisk (*) indicates that the value is significantly different from the activity of DMSO.