Computer-aided analyses found a putative T cell factor/lymphoid enhancer factor (TCF/LEF) binding site, i.e. CTTTGA, at -275bp to -269bp within the promoter region. TCF/LEF binding sites are targets of canonical Wnt signaling and bound by a complex of β-catenin with TCF/LEF, mediating the regulation of target gene transcription 42, 43. The plasmid pLOX-1(mut)-Luc with site-directed mutation in the TCF/LEF-1 binding site was generated from the parental plasmid pLOX-1-Luc. Passaged HSCs were transfected with pLOX-1-Luc or pLOX-1(mut)-Luc and subsequently treated with or without curcumin (20 μM) for 24 hr. Luciferase activity assays in Fig. 6B demonstrated that compared to the untreated control, curcumin significantly reduced, as expected, luciferase activities by 50.5% in cells transfected with wild-type pLOX-1-Luc. However, the site-directed mutation of the TCF/LEF-1 binding site in pLOX-1(mut)-Luc resulted in a significant reduction from ∼50% to ∼25% in the difference of luciferase activities between cells treated with or without curcumin, indicating a significant loss in response to curcumin. In addition, compared to pLOX-1-Luc, pLOX-1(mut)-Luc also led to an apparent reduction in luciferase activities in cells without curcumin treatment, suggesting an important role of the TCF/LEF-1 binding site in regulating the basal promoter activity of LOX-1 in HSCs. Taken together, these results suggested that the TCF/LEF-1 binding site might be responsible for both controlling the basal promoter activity, as well as responding to the curcumin treatment, i.e. a major curcumin response element, which played a critical role in the curcumin-caused inhibition of the lox-1 promoter activity.