Primary murine embryonic fibroblasts (MEFs) were stimulated with 1000 U/ml murine IFN-b (PBL, Inc., Piscataway, NJ) for 16 h and lysed in lysis buffer [50 mM Tris pH 7.6, 150 mM NaCl, 0.5% Triton X-100, 1 mM sodium orthovanadate, 10 mM sodium fluoride, 5 mM sodium pyrophosphate, 10 mM bglycerophosphate and 16 complete EDTA-free protease inhibitor (Roche, Indianapolis, IN)]. 10 mg of whole cell extract were separated via 10% SDS-PAGE, transferred to PVDF membranes, blocked with 5% dry milk in Tris-buffered saline/0.05% Tween-20 overnight and labeled with anti-Ifit3/P49, anti-Ifit2/P54 or anti-Ifit1/P56 polyclonal rabbit sera [17, 38] .