At different times after viral infection, cells were lysed in lysis buffer (4 M urea, 1 mM MgCl 2 , 50 mM HEPES, and 100 U benezonase/ 10 7 cells). Lysates containing the equivalent of 2610 5 cells per lane were separated by electrophoresis on 10% polyacrylamide gels and electrotransferred onto polyvinylidene difluoride membranes overnight. The membrane was blocked with 5% fat-free milk in a TBST solution for 1 h and then probed separately with a mouse monoclonal antibody (mAb) against Oct-4 (Santa-Cruz Biotechnology, Santa Cruz, CA, USA) at a concentration of 0.2 mg/mL, 1:1000 of an anti-GFAP rabbit polyclonal antibody (pAb; Chemicon International, Temecula, CA, USA), and 1:500 of an anti-glutamine synthetase mouse mAb (Chemicon International). Mouse b-actin was used as an internal control (Sigma). Horseradish peroxidase (HRP)-conjugated anti-mouse immunoglobulin G (IgG) and anti-rabbit IgG (Sigma) were used as the secondary antibodies. Signals were detected using an enhanced chemiluminescence (ECL) kit (Perkin Elmer, Wellesley, MA, USA).