Left: Immunofluorescence analysis of HeLa cells costained with mouse antibody to Ki-67 (1:2,000, red) and chicken antibody to vimentin (C-1409-50, 1:10,000, green). Ki-67 protein is predominantly localized in nucleoli of _cells in interphase, while in mitotic cells Ki-67 is associated with condensed chromosome. Ki-67 is not expressed in cells in quiescent G0 state. Blue: DAPI staining of nuclear DNA. Right: Western blot analysis of equal amounts of HeLa (Lane 2) and HEK293 (Lane 3) cell lysates probed with mouse antibody to Ki-67 (1:2,000, Lanes 2 and 3). Two bands above 250 kDa are observed, corresponding to major Ki-67 isoforms of molecular weight ~345 and 395 kDa.