ES cell-derived hepatocytes in aggregate suspension culture show improved induction and metabolize xenobiotics: (A) CYP1A2 and 3A4 induction by two prototypical inducers, omeprazole, and rifampicin, is significantly increased in suspension culture of ES cell-derived hepatocytes compared with adherent culture, where it is almost absent. HepG2 cells, even in suspension fail to show much induction, whereas primary human hepatocytes (PHHs) display variability between culture conditions. Gene expressions were measured by QPCR, normalized to GAPDH and expressed in RQ (relative quantity), with error bars representing RQ min and RQ max derived from standard error. Fold-induction was calculated by comparing experimental samples against control untreated samples. (B) Metabolism of the two above drugs as quantified by the amount of metabolites secreted into the media/cell by LC-MS/MS. Adherent cultured primary human hepatocytes have been set to 100%. ES cell-derived hepatocytes in aggregate suspension metabolize the two drugs to their human-specific metabolites whereas HepG2 cells generates only 5-hydroxy omeprazole above background levels. Metabolism is totally absent in negative control 293 cells.