CINPA1 (CINPA 1) is a selective inhibitor of constitutive androstane receptor (CAR) with an IC50 of 70 nM for CAR-mediated transcription. CINPA1 can be used in studies about CAR function.

CINPA1 is a specific xenobiotic receptor inhibitor and has no cytotoxic effects up to 30 μM. CINPA1 inhibits CAR-mediated gene expression in primary human hepatocytes, where CAR is endogenously expressed and it efficiently inhibits CAR-LBD interaction with the coactivator peptide. CINPA1 (1μM) inhibits CAR-mediated transactivation without activating the pregnane X receptor (PXR) in HepG2 cells. In mammalian two-hybrid assays, CINPA1 increases the corepressor and reduces coactivator interaction with the CAR ligand-binding domain. In chromatin immunoprecipitation assays, CINPA1 disrupts CAR binding to the promoter regions of target genes[1].