This antibody validation report summarizes an immunofluorescence analysis of an anti-E2F-1 polyclonal antibody in rat heart tissue. The antibody was diluted at 1:200 and incubated overnight at 4°C, followed by incubation with a Cy3-labeled secondary antibody at 1:300 for 50 minutes at room temperature. Images show the target labeling in red and DAPI nuclear counterstain in blue. The report also describes the immunofluorescence protocol used, including tissue processing, antigen retrieval, blocking, primary and secondary antibody incubations, counterstaining, mounting, and visualization under a fluorescence microscope.