The Brd4 ET domain associates with several multiprotein complexes. HA immunoprecipitations were performed with lysates from 293T cells stably expressing HA-GLTSCR1, HA-ATAD5, HA-NSD3, HA-JMJD6, or HA-CHD4, and the bound proteins were subjected to mass spectrometry and CompPASS analysis (MS or IP).