TRIM28 and infection: Western blot analysis revealed that all three (PIV2, PIV5, IAV) infections induced phosphorylation of TRIM28 at S824 (Fig 4A, B), suggesting that infection with each of these viruses results in a cellular stress response similar to that induced by the DNA damage-causing molecule etoposide, which served as a positive control for TRIM28 S824 phosphorylation.