Subsequently, Elsen and co-workers [8] demonstrated that infection with different P. aeruginosa strains causes DNA strand breaks and phosphorylation of histone H2AX and its co-localization with the 53BP1 protein in terminally differentiated macrophages, and in actively proliferating lung cancer epithelial cells at 1.5 h–2.5 h post-infection. Here, H2AX is linked to infection.