Cells were treated with transcriptional inhibitors, ActD (Sigma) (5 mg/ml) or a-amanitin (Sigma) (50 mg/ml) immediately after infection or transfection. To induce the inhibition of proteasome function, cells were immediately treated with MG132 (Sigma) at 10 mM or lactacystin (Sigma) at 50 mM after infection or transfection. To suppress PKC activity, cells were treated with a general PKC inhibitor, GÖ 6983 (Calbiochem) at 100 nM immediately after infection with rMP12-rLuc or MP-12. Cells were treated with puromycin (Cellgro) at 100 mg/ml immediately after infection or transfection to inhibit cellular translation.