Bile acid or drug-induced cholestasis may lead to activation of pregnane X receptor (PXR) which induces human cytochrome P4503A4 to catalyze 6-hydroxylation of bile acids for renal excretion (Gnerre et al. 2004; Li and Chiang, 2005; Li and Chiang, 2006). Here, NR1I2 is linked to cholestasis.