TP53 and influenza: In this study, by generating p53null lung epithelial cell lines from A549 cells carrying wild-type p53 alleles using the new genome-editing technology CRISPR/Cas9 (15), we were, for the first time, able to compare in parallel the response to influenza infection in an isogenic background of p53WT and p53null human cells that are permissive to influenza virus infection.