As a control, vΔD9 infection of A549DKO cells barely induced the highly accumulated cap regions in the cytoplasm (<1%) (Fig. 6D); however, it led to an increase of 5′-cap staining in the nuclei of some cells (Fig. 6D), suggesting that D9 plays a role to remove RNA 5′ cap in nuclei, an intriguing phenotype prompting further investigation of the different roles of D9 and D10 in subcellular organelles during infection. This evidence concerns the gene CENPX and infection.