A) flag-FXR (upper panel) or acetylated flag-FXR (lower panel) was detected in Cos-1 cell extracts. B) Increasing amounts of cell extracts were incubated with flag-RXRα and the radiolabeled oligonucleotide probe containing the FXRE from the SHP promoter, and complexes were detected using gel mobility shift (gms) assay. C) Experimental outline for the gms using flag-FXR acetylated in vitro. D, E) Purified flag-FXR was incubated with p300 (−/+ acetyl CoA). In D, acetylated flag-FXR was detected by western analysis. In E, increasing amounts of unacetylated or acetylated flag-FXR were incubated with purified RXRα and the complexes were detected. F, G) Cos-1 cells were cotransfected with expression plasmids as indicated with p300 plasmids and expressed protein levels were determined. Interaction between flag-FXR and RXRα was detected by CoIP assays.