Patent ID: 6911537

Claim:
An expression system comprising: at least one SXR response element operably linked to at least one gene, and a nuclear receptor which is a member of the steroid/thyroid hormone superfamily and which responds to xenobiotic compounds and binds to said at least one SXR response element as a heterodimer with retinoid X receptor (RXR) to activate transcription of said at least one gene; wherein said at least one SXR response element comprises a direct or inverted repeat response element comprising at least two half sites RGBNNM separated by a spacer of 0 up to 15 nucleotides wherein: R is selected from A or G; B is selected from G, C, or T; each N is independently selected from A, T, C, or G; and M is selected from A or C; with the proviso that at least 4 nucleotides of said -RGBNNM-sequence are identical with the nucleotides at corresponding positions of the sequence AGTTCA.