VOLUME 285 (2010) PAGES 16096–16104
In Fig. 2A, results from two different immunoblots were spliced together without declaration. This figure was corrected by adding a line between the two immunoblots. In Fig. 6B and Fig. S4, some cells from the same field were rearranged. These errors have now been corrected. Finally, the treatment time for PS-341 in Fig. S4 should be 8 h, not 4 h as indicated in the original figure legend. This error was corrected as well. These corrections do not affect the results or conclusions of this work.