Influenza virus is known to induce apoptosis during later stages of infection in order to facilitate effective viral propagation and dissemination.34 Concurrent with these findings, we observed a time-dependent increase in APAF1 protein levels, cleaved forms of both caspases 9 and 3 in infected cells (Figure 4a), indicative of progressive apoptosis. This evidence concerns the gene CASP9 and infection.