Deletion of the mTORC1 target 4EBP1 rescues replication of MCMV in the presence of Torin1. (A) MCMV growth is not inhibited by Torin1 in 4EBP1-null MEFs. Confluent serum-starved cells were infected with MCMV at a multiplicity of 0.05 PFU/cell, and vehicle (black bars) (DMSO), rapamycin (gray bars) (20 nM), or Torin1 (white bars) (250 nM) was added at 1 hpi. At 6 days postinfection the amount of MCMV in cell-free supernatants was determined by the TCID50 method. The error bars represent the standard errors of the means from three independent experiments, each performed in duplicate. (B) Torin1 does not exclude eIF4G or eIF4A from the cap-binding complex in 4EBP1-null MEFs. Cells were infected with MCMV at a multiplicity of 3 PFU/cell and treated with vehicle (N), rapamycin (R), or Torin1 (T) as described above (A). At 48 hpi equal amounts of protein from cell lysates were incubated with m7G-Sepharose. The presence of eIF4F complex components bound by the cap analog was determined by Western blotting. The results are representative of two independent experiments.