ERR activity modulation by compounds in the statin cluster. (a) An ERR-luciferase assay was conducted by cotreating the known ERR inverse agonist, XCT790, at concentrations of 0 μM, 5 μM, or 10 μM with atorvastatin (23 μM), atorvastatin calcium (23 μM), cerivastatin sodium (23 μM), fluvastatin (23 μM), lovastatin (23 μM), or simvastatin (46 μM). The activities were compared with each respective compound without cotreatment of XCT790. (b) A knockdown ERR-luciferase assay was performed by transfecting ERR cells with either control or ERR siRNA. Cells were then treated with DMSO (0.2%), cerivastatin sodium (569 nM), or fluvastatin (15 μM). Each bar represents the mean ± standard deviation (n = 3). *P < 0.05, **P < 0.01, ***P < 0.001. ns, not significant.