RNF168 interacts with LSD1. (a) RNF168 was immunoprecipitated using Flag or control antibody from nuclear extract prepared from 293T cells stably expressing Flag-HA-RNF168, with or without irradiation as indicated. Western blotting was then performed against Flag or endogenous LSD1. Arrow indicates the Flag-HA-RNF168, which is expressed at relatively low levels. (b) Myc-RNF168 and HA-LSD1 were coexpressed, and LSD1 was immunoprecipitated using an HA antibody, followed by Western blotting as indicated. (c) Immunprecipitation was performed as in panel a from nocodazole-arrested 293T cells mock infected or stably expressing Flag-HA-RNF8 or Flag-HA-RNF168 as indicated. (d) Tagged wild-type LSD1 or NΔ-171 LSD1 were stably expressed in U2OS cells, microirradiated, incubated for 15 min, and then stained for HA and pH2A.X. Bar, 20 µm. (e) Immunprecipitation was performed from 293T cells expressing the indicated vectors, followed by Western blotting as indicated.