27 nor 5 cholestenoic acid Article Binding Sites Cholestenes Cholestenoic acid Gene Expression Regulation HEK293 Cells HEK293 cell line Hep G2 Cells HepG2 cell line Humans Inverse agonism Ligands Liver X receptors Molecular dynamics Orphan Nuclear Receptors antagonists and inhibitors binding site carboxyl group cholestane derivative cholestenoic acid cholesterol conformational transition drug effects gene expression gene expression assay gene expression regulation genetics human in vitro study