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ed using the Luciferase Assay System protocol and a luminometer. b-galactosidase activity was detected using a colorimetric enzyme assay using the Luminescent b-Galactosidase Detection Kit II according to the manufacturer's instructions. Luciferase expression levels were normalized to the levels of b-galactosidase expression. Western blot analysis Cells were solubilized in radioimmunoprecipitation