EIF2AK2 and infection: Infection of H4 cells expressing mRuby-PKR with a mutant MV strain (MVCKO) that potently activates PKR (Okonski and Samuel, 2013; Toth et al., 2009; Pfaller et al., 2014) induced mRuby-PKR cluster assembly within ∼38 h, which is consistent with the timeline of viral replication tracked by GFP signal (Pfaller et al., 2014; Fig. 1, F and G).