CDCA effects on R2C cell proliferation. A, R2C cells were treated with vehicle (−) or 50 and 100 μm CDCA for 24 and 48 h, or B, transiently transfected with FXR dominant negative (FXR-DN) for 24 h and then treated as reported above, or C, transfected with control siRNA or FXR siRNA for 24 h and treated for 24 h with 50 and 100 μm CDCA. Thymidine incorporation assay was performed. The results represent the mean ± S.D. (error bars) of three different experiments each performed with triplicate samples, and expressed as percentage of growth versus control, which was assumed to be 100%. *, p < 0.01 compared with vehicle.