STAT5 protein interacts with LEF-1 protein. Whole-cell lysates of HEK293 cells co-transfected with expression plasmids for LEF-1 and caSTAT5a complementary DNA (A) or WT STAT5a (B) were immunoprecipitated (IP) with rabbit monoclonal anti–LEF-1 antibody (IP-antibody) and were further analyzed by western blotting (WB) using a mouse monoclonal anti–LEF-1 or mouse monoclonal anti-STAT5a antibody. Representative images are shown. (C) Jurkat cell lysates were immunoprecipitated with a polyclonal anti–LEF-1 antibody and the immunoprecipitates were subjected to WB analysis with monoclonal anti–LEF-1 antibody or polyclonal anti-STAT5a antibody. Lysates of Jurkat cells used for immunoprecipitation were included as a positive control. Representative WB images are shown. (D) The interaction of endogenous LEF-1 and STAT5a proteins in CD34⁺ cells from healthy individuals incubated with or without 10 ng/mL of G-CSF was detected using a Duolink In Situ Proximity-Ligation Assay. (Left) DAPI-stained nuclei; (middle) Cy3 dots corresponding to LEF-1–STAT5a interaction; (right) DAPI/Cy3 overlay with red dots corresponding to LEF-1–STAT5a interaction. Ig, immunoglobulin.