Fig. 2. Nucleolar localization of endogenous CTCF in human breast cancer cells treated with sodium butyrate. (A) Indirect immunofluorescent staining showing CTCF nucleolar localization following treatment of MCF7 cells with sodium butyrate (NaBu). After induction with 5 mM NaBu for 8 hours, MCF7 cells were immunostained with the anti-CTCF rabbit polyclonal antibody (a,d) or stained with DAPI (b,e); (c,f) merged images of CTCF and DAPI staining. (a-c) Untreated MCF7 cells (control); (d-f) MCF7 cells treated with NaBu. Bar, 10 µm. (B) Nucleolar fractionation and western analysis of MCF7 cells treated with NaBu. MCF7 cells were treated with 5 mM sodium butyrate for 8 hours, nucleolar fractions were isolated and western analysis with the rabbit polyclonal anti-CTCF antibody was performed. Total, whole cell extract; Np, nucleoplasmic fraction; NO, nucleolar fraction; Cyto, cytoplasmic fraction.