Western blot analysis of extracts of Slx4-/- MEF which were infected with retroviruses expressing SLX4 wildtype (SLX4), SLX4 bearing alanine mutaions at Y1340, L1348 or E1351 + L1352. Upper panel: Extracts were immunoblotted with Anti-SLX4 (1266 – end mouse) S819C, anti-ERCC1 (1-200 mouse) S161D, anti-MUS81 (1-200 mouse) S163D and anti-EME1 (1 – 200 mouse) S166D. Lower panel: Eaxtracts were immunoprecipitation with anti-SLX4 (1266 – end mouse) S819C before being immunoblotted with anti-SLX4 (1266 – end mouse) S819C, anti-ERCC1 (1-200 mouse) S161D, anti-MUS81 (1-200 mouse) S163D and anti-EME1 (1 – 200 mouse) S166D anti-SLX1 (mouse) S778C