Hepatic expression of PXR target genes involved in microsomal bile acid metabolism (CYP3A29) and organic ion efflux (MRP2) in preterm piglets after 14 days of treatment with PN plus the following: Intralipid (IL), Intralipid plus vitamin E (ILE), Omegaven (OV), or Omegaven plus phytosterols (PS). Quantitative RT-PCR analysis shows relative transcript levels of mRNA. Values are means ± SEM; n = 8–10 pigs/group. Differences between treatment groups were analyzed using ANOVA, Kruskal-Wallis, and Mann-Whitney U tests; *P < .05 vs IL. ANOVA, analysis of variance; CYP3A29, cytochrome P450 3A29; MRP2, multidrug resistance-associated protein 2; PN, parenteral nutrition; PXR, pregnane X receptor; RT-PCR, real-time polymerase chain reaction; SEM, standard error of the mean.