Using reconstitution assays in A549 lung cancer cells upon IAV infection, the authors showed that KAP1 knockout using CRISPR-Cas9 led to decreased viral replication, and that KAP1, but not KAP1 mutated at 6 Lysine residues capable of getting SUMOylated (named SUMO mutant), could rescue replication levels upon KAP1 loss, suggesting that SUMOylation is critical for productive IAV infection. This evidence concerns the gene TRIM28 and lung carcinoma.