Activation of FXR results in transient, temporally correlated induction of intestinal Fgf15 and hepatic βKL in mice in vivo. A and B, C57BL/6 WT mice were fasted for 12 hours and, then, ip injected with GW4064 for the indicated times before killing. Pre-mRNA (A) and mRNA levels (B) of Fgf15 in the intestine and liver, and of βKL, Shp, and Cyp7a1 in the liver were determined by q-RT-PCR (SEM, n = 3; *, P < .05; **, P < .01; ***, P < .005). C and D, WT and FXR-KO mice were injected with GW4064 for the times indicated and protein levels of intestinal FGF15 (C) and hepatic βKL and FGFR4 (D) were detected by IHC.