Hyperubiquitylation of APC in Trabid-depleted cells. Western blots of nuclear or cytoplasmic fractions 24 h after transfection of 293 (A,B,D) or 293T (C) cells transfected with siRNAs (A–D) (as in Fig. 4F) and HA-ubiquitin (B); treated for 4 h with DMSO (control), 10 mM MG132, and/or 20 mM LiCl or Wnt3A-conditioned medium as indicated; and probed sequentially with the antibodies indicated on the right. (E) Coimmunoprecipitations from nuclear fractions from 293T cells (200 μg), prepared as in C, as indicated.