Fig. 2. Comparison of nucleolar TRF2 with UBF and B23 in human MCF-7 cells. The colocalization of these proteins was probed by double-immunofluorescence of TRF2 and UBF (A-C) or B23 (F-H). The reorientation of TRF2, UBF, and B23 was measured after applying 0.05 µg/ml actinomycin D for 3 hours and following the signals of TRF2 and UBF (D-E) or TRF2 and B23 (I-J). The colocalization of TRF2 with UBF in C-C' or B23 in F-H was observed by laser scanning confocal microscopy. Red and green arrows in C' and H represent TRF2 and UBF or B23, respectively. The frames presented in A-B and D-E are the magnification of the arrow-indicated nucleoli of the same picture. Smaller arrows in the frames of D-E indicate the relocalization of UBF after actinomycin D treatment. Fluorescence measurements along the dashed lines in C' and H are presented in C'' and H'.