Indirect immunofluorescence analysis. P3HR1 cells were transfected with pEGFP-C1 (A–D) or pEGFP-TAF4 (E–H) and then treated with sodium butyrate for 24 hr. Cells were incubated with monoclonal anti-Rta antibody and observed under a confocal laser-scanning microscope. DAPI staining revealed the positions of nuclei (A and E). D and H are merged images.