The ileal bile acid-binding protein (I-BABP, also known as FABP6) is encoded by FABP6 gene. FABP6 is a 14 kDa cytosolic protein which binds bile acids with a high affinity. FABP6 gene expression was directly up-regulated by liver X-receptor α (LXRα or NR1H3) and LXRβ (NR1H2) in human enterocyte-like Caco-2 cells when the cells were transiently cotransfected with a FABP6 promoter fragment cloned upstream of the CAT reporter gene and expression vectors for NR1H3 or NR1H2 and retinoid X receptor α (RXRα) (Landrier JF et al. 2003). Electrophoretic mobility shift assays demonstrated that the NR1H3:RXR heterodimer specifically recognized a farnesoid X‐receptor‐responsive element (FXRE) which functioned as an LXR responsive element (LXRE) in the promoter of FABP6 gene (Landrier JF et al. 2003). Similar data have been reported for the PLTP gene suggesting that the FXRE sequence can function as an LXR‐binding site in different genes (Mak PA et al. 2002). Besides, FABP6 gene expression can be indirectly up-regulated by cholesterol through the activation of sterol-responsive element-binding protein 1c (SREBP1c) by liver X-receptors (Zaghini I et al. 2002).