ETO colocalizes with Bcl-6 in vivo. (A) 293T cells were cotransfected with levels of ETO and Bcl-6 that reproduce the endogenous nuclear staining pattern of both proteins. Immunofluorescence visualization was achieved by exposing the cells to ETO polyclonal antibody and Bcl-6 monoclonal antibody, followed by Alexa 488 (green)– and Alexa 568 (red)–labeled secondary antibodies, respectively. Cell sections were visualized at × 60 magnification using laser scanning confocal microscopy. Panels show the visualization of ETO or Bcl-6 alone and the overlay of both images in the lower panel. (B) Daudi cells were treated with the same antibodies to detect localization of endogenous ETO and Bcl-6 by immunofluorescence. Cell sections were visualized by confocal microscopy at × 60 magnification, as described for panel A.