Western blotting was performed as previously described (10 (link)). We used the following primary antibodies: rabbit polyclonal antibody specific for PARP, phospho-TBK1/NAK (Ser172), TBK1, phospho-polo-like kinase-1 (PLK1) (Thr210), and PLK1from Cell Signaling (Beverly, MA), and β-actin antibody from Sigma (St. Louis, MO).