The RA1 domain of AF6 mediates self-association in vitro. (A) Self-association was assessed by anti-HA Western blot analysis after anti-FLAG immunoprecipitation from lysates of 293 cells cotransfected with various HA-tagged AF6 constructs together with FLAG-tagged AF6^RA1 (top). Expression levels of the relevant input proteins were determined by immunoblotting with either anti-HA (middle) or anti-FLAG (bottom) antibodies. (B) Self-association of MLL-AF6^RA1 was shown by anti-HA Western blot analysis after anti-FLAG immunoprecipitation from lysates of cells cotransfected with HA-tagged MLL-AF6^RA1 and FLAG-tagged MLL-AF6^RA1 (top). Expression levels of the input proteins were determined with either anti-HA (middle) or anti-FLAG (bottom) antibodies.