FIG. 9.
Working model for NS action. The model is based on past and present results as detailed in Discussion. In brief, stimulation of RSV growth may result from (i) subversion of IFN signaling by NS proteins and (ii and iii) suppression of premature apoptosis by the NS-dependent PI3K→AKT→NF-κB pathway and NS-independent EGFR→ERK pathway. These pathways are incomplete, and multiple crossovers are possible but not shown to avoid complexity. Notable among them are sphingosine kinase, which mediates the activation of ERK and AKT (30), and multiple protein kinase C isoforms that play an important role in activating ERK and NF-κB (5, 29).